CHAPTER 5. ENGINEERING ANALYSIS

TABLE O F CONTENTS

5.1 INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­1

5.2 STRUCTURING THE ENG INEERING ANALYSIS

. . . . . . . . . . . . . . . . . . . . . . . . . . . 5­1

5.2.1 Summary o f Design Line Coverage

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­7

5.2.2 Scaling R elationships in Transformer Manufacturing

. . . . . . . . . . . . . . . . . . . . . . 5­9

5.3 TECHNICAL D ESIGN INPUTS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­12

5.3.1 Design L ine 1 Representative Unit

5.3.2 Design L ine 2 Representative Unit

5.3.3 Design L ine 3 Representative Unit

5.3.4 Design L ine 4 Representative Unit

5.3.5 Design L ine 5 Representative Unit

5.3.6 Design L ine 9 Representative Unit

5.3.7 Design L ine 10 Representative Unit

5.3.8 Design L ine 11 Representative Unit

5.3.9 Design L ine 12 Representative Unit

5.3.10 Design L ine 13 Representative Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­18

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­19

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­20

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­25

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5.4 MATERIAL A ND LABOR INPUTS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­28

5.4.1 Material P rices

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­30

5.4.2 Material I nputs to the Design Software—Liquid­Immersed

. . . . . . . . . . . . . . . . 5­31

5.4.3 Material I nputs to the Design Software—Dry­type

. . . . . . . . . . . . . . . . . . . . . . . 5­34

5.4.4 Labor C osts

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­38

5.5 RESULTS O F THE ANALYSIS ON EACH DESIGN LINE

. . . . . . . . . . . . . . . . . . . . . 5­45

5.6 TEAR­DOWN ANALYSIS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­56

5.7 REVIEW O F AMORPHOUS MATERIAL PRICING

. . . . . . . . . . . . . . . . . . . . . . . . . . 5­57

Table 5 .2.1

Table 5.2.2

Table 5.2.3

Table 5.2.4

Table 5.2.5

Table 5.2.6

Table 5.3.1

Table 5.3.2

Table 5.3.3

Table 5.3.4

Table 5.3.5

Table 5.3.6

Table 5.3.7

Table 5.3.8

Table 5.3.9

Table 5.3.10 LIST O F TABLES

Product C lasses and Number of kVA Ratings

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­2

E ngineering Design Lines (DLs) and Representative Units for Analysis

. . . . . . . 5­3

L iquid­Immersed Design Lines and Representative Units

. . . . . . . . . . . . . . . . . . 5­7

D ry­Type, Medium­Voltage, Single­Phase Design Lines

. . . . . . . . . . . . . . . . . . . 5­8

D ry­Type, Medium­Voltage, Three­Phase Design Lines

. . . . . . . . . . . . . . . . . . . . 5­9

C ommon Scaling Relationships in Transformers

. . . . . . . . . . . . . . . . . . . . . . . . 5­10

A and B Grid Combinations used by Software to Generate Design Database

. . 5­13

A and B Fan Combinations used by Software to Generate Design Database

. . . 5­14

Core Steel Grades, Thicknesses and Associated Losses

. . . . . . . . . . . . . . . . . . . 5­15

C ore Configurations Used in Each Design Line

. . . . . . . . . . . . . . . . . . . . . . . . . 5­16

Design O ption Combinations for the Representative Unit from Design Line 1

. 5­19

Design O ption Combinations for the Representative Unit from Design Line 2

. 5­20

Design O ption Combinations for the Representative Unit from Design Line 3

. 5­21

Design O ption Combinations for the Representative Unit from Design Line 4

. 5­22

Design O ption Combinations for the Representative Unit from Design Line 5

. 5­23

Design O ption Combinations for the Representative Unit from Design Line 9

. 5­24

5­iTable 5.3.11 Design O ption Combinations for the Representative Unit from Design Line 10

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­25

Table 5 .3.12 Design O ption Combinations for the Representative Unit from Design Line 11

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Table 5 .3.13 Design O ption Combinations for the Representative Unit from Design Line 12

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­27

Table 5 .3.14 Design O ption Combinations for the Representative Unit from Design Line 13

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­28

Table 5 .4.1 Manufacturer’s M aterial Prices for Liquid­Immersed Design Lines

. . . . . . . . . . 5­31

Table 5 .4.2 Marked­up M aterial Prices for Liquid­Immersed Units, Five­Year Average Price

Scenario

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­32

Table 5 .4.3 Summary T able of Fixed Material Costs for Liquid­Immersed Units

. . . . . . . . . 5­34

Table 5 .4.4 Manufacturer’s M aterial Prices for Dry­Type Design Lines

. . . . . . . . . . . . . . . . 5­35

Table 5 .4.5 Marked­up M aterial Prices for Dry­Type Units, Five­Year Average Price Scenario

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­36

Table 5 .4.6 Summary T able of Fixed Material Costs for Dry­Type Units

. . . . . . . . . . . . . . . 5­38

Table 5 .4.7 Labor M arkups for Liquid­Immersed and Dry­Type Manufacturers

. . . . . . . . . . 5­39

Table 5 .4.8 Summary o f Labor Times for Liquid­Immersed Units

. . . . . . . . . . . . . . . . . . . . 5­42

Table 5 .4.9 Summary o f Labor Times for Dry­Type Units

. . . . . . . . . . . . . . . . . . . . . . . . . . . 5­44

Table 5 .7.1 Forty­foot C ontainer from Conway, SC to Guragaon, India

. . . . . . . . . . . . . . . . 5­58

Table 5 .7.2 Forty­foot C ontainer from Guragaon, India to Inland US Location

. . . . . . . . . . 5­59

Table 5 .7.3 Summary o f Shipping and Processing Costs for Finished Amorphous Core

. . . 5­59

LIST O F FIGURES

Figure 5 .3.1 A and B Combination Software Inputs used in the Engineering Analysis

. . . . . 5­14

Figure 5 .3.2 Graphic o f Single­Phase Core Configurations

. . . . . . . . . . . . . . . . . . . . . . . . . . . 5­16

Figure 5 .3.3 Graphic o f Three­phase Core Configurations

. . . . . . . . . . . . . . . . . . . . . . . . . . . 5­17

Figure 5 .3.4 Cruciform C ore Cross­Section

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­17

Figure 5 .4.1 Standard M ethod of Cost Accounting for Standards Rulemaking

. . . . . . . . . . . . 5­28

Figure 5 .5.1 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­46

Figure 5 .5.2 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­47

Figure 5 .5.3 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 3

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­48

Figure 5 .5.4 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­49

Figure 5 .5.5 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­50

Figure 5 .5.6 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 9

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­51

Figure 5 .5.7 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 10

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­52

Figure 5 .5.8 Engineering A nalysis Results, 2002­2006 Average Material Prices, Design Line 11

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­53

5­iiFigure 5.5.9 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 12

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­54

F igure 5.5.10 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 13

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F igure 5.6.1 Tear­down Plot Comparison, Design Line 7, 75kVA Three­phase Dry­type

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5­57

5­iiiCHAPTER 5. ENGINEERING ANALYSIS

5.1 INTRODUCTION

This c hapter provides the technical support documentation on the engineering analysis,

evaluating both liquid­immersed and dry­type distribution transformers. The purpose of the

engineering analysis is to estimate the relationship between the manufacturer’s selling price of a

transformer and its corresponding efficiency rating. This relationship serves as the basis for the

subsequent cost­benefit calculations for individual consumers, manufacturers, and the nation (see

Chapter 8, Life­Cycle Cost and Payback Period Analyses).

5.2 STRUCTURING T HE ENGINEERING ANALYSIS

As d iscussed in the market and technology assessment (Chapter 3), distribution transformers

are classified by their insulation type (liquid­immersed or dry­type), the number of phases (single or

three), and the basic impulse insulation level (BIL) rating (for dry­types). Following this

convention, the Department developed eight product classes, shown in Table 5.2.1. These product

classes were adapted from the National Electrical Manufacturers Association (NEMA)’s TP 1

classification system, although they do not follow the classification system precisely. NEMA’s TP

1 classifies medium­voltage, dry­type distribution transformers into two product classes, < 60

kilovolt (kV) BIL and >60 kV BIL. Based on input from manufacturers, the Department elected to

increase the differentiation of medium­voltage, dry­type transformers, and create three product

classes of BIL ratings: 20–45 kV BIL, 46–95 kV BIL, and >96kV BIL (see section 3.3).

Within e ach of these product classes, distribution transformers are further classified by their

kilovolt­ampere (kVA) rating. These kVA ratings are essentially size categories, indicating the

power handling capacity of the transformers. Due to the construction methods and material

properties, efficiency levels vary by both product class and kVA rating. For NEMA’s TP 1­2002, a

there are 99 kVA ratings across all the product classes (see section 3.7.1). For the Department’s

rulemaking, because of the greater degree of differentiation around the BIL rating in mediumvoltage, dry­type transformers, there are 95 kVA ratings across all the product classes, as shown in

Table 5.2.1.

a NEMA’s TP 1­2002 can be found online at: http://www.nema.org/stds/tp1.cfm#download

5­1Table 5.2.1 Product Classes and Number of kVA Ratings

Number of kVA Distribution Transformer P roduct Class kVA R ange Ratings

1. L iquid­immersed, medium­voltage, single­phase 10

– 833 13

2. L iquid­immersed, medium­voltage, three­phase 15

– 2500 14

5. D ry­type, medium­voltage, single­phase, 20­45 kV BIL 15

– 833 12

6. D ry­type, medium­voltage, three­phase, 20­45 kV BIL 15

– 2500 14

7. D ry­type, medium­voltage, single­phase, 46­95 kV BIL 15

– 833 12

8. D ry­type, medium­voltage, three­phase, 46­95 kV BIL 15

– 2500 14

9. D ry­type, medium­voltage, single­phase, > 96 kV BIL 75

– 833 8

10. D ry­type, medium­voltage, three­phase, > 96 kV BIL 225

– 2500 8

Total 95

The Department recognized that it would be impractical to conduct a detailed engineering

analysis of the manufacturer’s selling price­efficiency relationship on all 95 kVA ratings, so it

sought to develop an approach that simplified the analysis while retaining reasonable levels of

accuracy. The Department consulted with industry representatives and transformer design

engineers, and developed an understanding of the construction principles for distribution

transformers. It found that many of the units share similar designs and construction methods. Thus,

the Department simplified the analysis by creating 10 engineering design lines, which group

together kVA ratings based on similar principles of design and construction. The 10 design lines

subdivide the product classes, to improve the accuracy of the engineering analysis. These 10

engineering design lines differentiate the transformers by insulation type (liquid­immersed or drytype), number of phases (single or three), and primary insulation levels for medium­voltage, drytype (three different BIL levels).

The D epartment then selected one unit from each of the engineering design lines for study in

the engineering analysis and the life­cycle cost (LCC) analysis (see Chapter 8), reducing the number

of units for analysis from 95 to 10. It then extrapolated the results of its analysis from the unit

studied to the other kVA ratings within that same engineering design line. The Department

performed this extrapolation in the national impacts analysis (see Chapter 10). The technique used

to extrapolate the findings on the representative unit to the other kVA ratings within a design line is

referred to as “the 0.75 scaling rule.” This rule states that, for similarly designed transformers, costs

of construction and losses scale to the ratio of kVA ratings raised to the 0.75 power. The

relationship is valid where the optimum efficiency loading points of the two transformers being

scaled are the same. An example of how DOE applied this scaling appears in section 5.2.1 of this

chapter. A technical discussion on the derivation of the 0.75 scaling rule appears in Appendix 5B.

Table 5 .2.2 presents the Department’s 10 design lines and the representative units selected

from each engineering design line for analysis. Descriptions of each of the design lines and the

rationale behind the selection of the representative units follow Table 5.2.2.

5­2Table 5.2.2 Engineering Design Lines (DLs) and Representative Units for Analysis

PC* DL Type o f Distribution kVA Representative U nit for this

Transformer Range Engineering D esign Line

1 Liquid­immersed, s ingle­phase,

rectangular tank 10

– 167 50 k VA, 65°C, single­phase, 60Hz, 14400V primary,

240/120V secondary, rectangular tank

1 2 Liquid­immersed, s ingle­phase,

round tank 10

– 167 25 k VA, 65°C, single­phase, 60Hz, 14400V primary,

120/240V secondary, round tank

3 Liquid­immersed, s ingle­phase 250

– 833 500 k VA, 65°C, single­phase, 60Hz, 14400V primary,

277V secondary

2 4 Liquid­immersed, th ree­phase 15

– 500 150 k VA, 65°C, three­phase, 60Hz, 12470Y/7200V

primary, 208Y/120V secondary

5 Liquid­immersed, th ree­phase 750

– 2500 1500 k VA, 65°C, three­phase, 60Hz,

24940GrdY/14400V primary, 408Y/277V secondary

6 9 Dry­type, m edium­voltage, threephase, 20­45kV BIL 15

– 500 300 k VA, 150°C, three­phase, 60Hz, 4160V Delta

primary, 480Y/277V secondary, 45kV BIL

10 Dry­type, m edium­voltage, threephase, 20­45kV BIL 750

– 2500 1500 k VA, 150°C, three­phase, 60Hz, 4160V primary,

480Y/277V secondary, 45kV BIL

8 11 Dry­type, m edium­voltage, threephase, 46­95kV BIL 15

– 500 300 k VA, 150°C, three­phase, 60Hz, 12470V primary,

480Y/277V secondary, 95kV BIL

12 Dry­type, m edium­voltage, threephase, 46­95kV BIL 750

– 2500 1500 k VA, 150°C, three­phase, 60Hz, 12470V

primary, 480Y/277V secondary, 95kV BIL

10 13 Dry­type, m edium­voltage, threephase, 96­150kV BIL 225

– 2500 2000 k VA, 150°C, three­phase, 60Hz, 12470V

primary, 480Y/277V secondary, 125kV BIL

* PC m eans product class (see Chapter 3 of the TSD). The Department calculated the analytical results for PC5, PC7,

and PC9 based on the results for their three­phase counterparts. The Department did not select any representative units

from the single­phase, medium­voltage product classes (PC5, PC7 and PC9) because of their low sales volume.

Liquid­immersed transformers are divided into five engineering design lines, based on their

tank shape, number of phases, and kVA ratings. The Department believes that this breakdown

enables the analysis to identify and capture a more accurate representation of the manufacturer’s

selling price and efficiency relationship. Dry­type distribution transformers are broken into five

engineering design lines, primarily according to their BIL levels. The Department believes this

level of disaggregation is necessary to capture important differences in the price­efficiency

relationship, particularly as the BIL level varies. For example, a 300 kVA, three­phase, dry­type

unit could be classified in design lines 9, 11, or 13, depending on whether the BIL rating is 20­45

kV, 46­95 kV, or 96­150 kV.

For d esign lines 9 through 13, the representative units selected for some of the dry­type

design lines may not be the standard BIL levels associated with a given primary voltage. The

Department selected a slightly higher BIL level for the representative units from these design lines

to ensure that any minimum efficiency standard would not excessively penalize customers

purchasing transformers at higher BIL ratings within the range. For example, a 300 kVA with a

4160V primary is called a “5kV class” transformer and would normally be built with a 30kV BIL

level. However, customers may also choose to order this transformer with 45kV BIL or 60kV BIL.

If the candidate minimum efficiency standard were set based on a 30kV BIL, it may not be possible

to achieve that same efficiency rating for customers ordering 60kV BIL. Thus, the Department

evaluated the middle BIL level (in this example, 45kV BIL), making it slightly easier to comply for

a lower BIL, and not too difficult (or impossible) for the higher BIL.

5­3The remainder of this section discusses each of the ten engineering design lines, providing a

description and explanation of the transformers covered.

Design L ine 1

. This is the basic, high­volume line for rectangular­tank, single­phase, liquidimmersed distribution transformers, ranging from 10 kVA to 167 kVA. Transformers in this design

line typically have BIL levels ranging from 30 kV to 150 kV and a tap configuration of four 21⁄2

percent taps—two above and two below the nominal voltage. Tap configurations enable

transformer users to maintain full (rated) output voltage by slightly increasing or decreasing the

number of turns in the primary in anticipation of an input voltage slightly above or below the rated

nominal. This design line has a primary voltage less than 35 kV, and a secondary voltage less than

or equal to 600 Volts (V).

The r epresentative unit selected for design line 1 is a 50 kVA pad­mounted unit, as this is a

high shipment volume rating, and is approximately the middle of the kVA range for this design line

(10 kVA, 15 kVA, 25 kVA, 37.5 kVA, 50 kVA, 75 kVA, 100 kVA, and 167 kVA). Engineering

design considerations and manufacturing differences led to the placement of 250 kVA and higherrated units in design line 3.

Design L ine 2

. This is the basic, high­volume line for round­tank (pole mounted), singlephase, liquid­immersed distribution transformers, ranging from 10 kVA to 167 kVA. Although

some manufacturers tend to employ the same basic core/coil design for design line 1 and design line

2, others may have design differences between pad­mounted and pole­mounted transformers. The

Department decided to analyze these two types of distribution transformers separately for the

engineering and LCC analyses. Transformers in this design line typically have BIL levels ranging

from 30 kV and 150 kV, a tap configuration of four 21⁄2 percent taps—two above and two below the

nominal, a primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.

The r epresentative unit selected for design line 2 is a 25 kVA pole­mounted unit, as this is a

high­volume rating for pole­mounted transformers, and is on the lower end of the kVA range for

this design line (10 kVA, 15 kVA, 25 kVA, 37.5 kVA, 50 kVA, 75 kVA, 100 kVA, and 167 kVA).

Engineering design considerations and manufacturing differences led to the placement of 250 kVA

and higher­rated units in design line 3.

Design L ine 3

. This design line groups together single­phase, round­tank, liquid­immersed

distribution transformers, ranging from 250 kVA to 833 kVA. Together, design lines 1 through 3

cover all the single­phase, liquid­immersed units (there are no standard kVA ratings between 167

and 250 kVA). Transformers in this design line typically have BIL levels ranging from 30 kV to

150 kV, a tap configuration of four 21⁄2 percent taps—two above and two below the nominal, a

primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.

The r epresentative unit selected for design line 3 is a 500 kVA round­tank, as this rating

occurs in the middle of the kVA range for this design line (250 kVA, 333 kVA, 500 kVA, 667 kVA,

and 833 kVA). Although high currents result with 277 V secondary at the larger kVA ratings,

high­current bushings are available, and a market does exist for these transformers.

Design L ine 4

. Design line 4 represents rectangular tank, three­phase, liquid­immersed

distribution transformers, ranging from 15 kVA to 500 kVA. Transformers in this design line

typically have BIL levels ranging from 30 kV to 150 kV, a tap configuration of four 21⁄2 percent

5­4taps—two above and two below the nominal, a primary voltage less than 35 kV, and a secondary

voltage less than or equal to 600 V.

The r epresentative unit selected for design line 4 is a 150 kVA transformer, as this is a

common rating in this design line and occurs approximately in the middle of the kVA range (15

kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, 150 kVA, 225 kVA, 300 kVA, and 500 kVA).

Design L ine 5

. Design line 5 represents rectangular tank, three­phase, liquid­immersed

distribution transformers, ranging from 750 kVA to 2500 kVA. Together, design lines 4 and 5

cover all the three­phase, liquid­immersed units (there are no standard kVA ratings between 500 and

750 kVA). Transformers in this design line typically have BIL levels ranging from 95 kV to 150

kV, a tap configuration of four 21⁄2 percent taps—two above and two below the nominal, a primary

voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.

The r epresentative unit selected for this design line is a 1500 kVA transformer, as this is a

common rating in this size range, and occurs in the middle of the kVA range for this design line

(750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA).

Design L ine 9

. Design line 9 represents three­phase, medium­voltage, ventilated dry­type

distribution transformers, ranging from 15 kVA to 500 kVA. To accommodate the broad kVA

range and to allow for engineering differences in construction principles and associated costs, the

Department split the three­phase, medium­voltage, dry­type units into design lines 9 and 10.

Transformers in this design line typically have primary voltages less than or equal to 5 kV with a

BIL rating between 20 kV and 45 kV. The secondary voltage is less than or equal to 600 V and the

tap arrangement is typically four 21⁄2 percent taps, two above and two below the nominal.

The r epresentative unit selected for design line 9 is 300 kVA, as this is a common rating in

this size range, and occurs near the high end of the kVA ratings for this design line (15 kVA, 30

kVA, 45 kVA, 75 kVA, 112.5 kVA, 150 kVA, 225 kVA, 300 kVA, and 500 kVA).

Design L ine 10

. Design line 10 represents three­phase, medium­voltage, ventilated dry­type

distribution transformers, ranging from 750 kVA to 2500 kVA. Transformers in this design line

typically have primary voltages less than or equal to 5 kV with a BIL rating between 20 kV and 45

kV. The secondary voltage is less than or equal to 600 V and the tap arrangement is typically four

21⁄2 percent taps, two above and two below the nominal.

The r epresentative unit selected for this design line is a 1500 kVA transformer, as this is a

common rating, and occurs in the middle of the kVA range for this design line (750 kVA, 1000

kVA, 1500 kVA, 2000 kVA, and 2500 kVA).

Design L ine 11

. Design line 11 represents three­phase, medium­voltage, ventilated dry­type

distribution transformers, ranging from 15 kVA to 500 kVA. This design line parallels design line

9, with a higher primary insulation level, 46 kV to 95 kV BIL. Because dry­type transformer

designs and, more importantly, the efficiency of those designs, are strongly influenced by changes in

BIL, the Department considered these higher BIL ratings separately. The typical tap arrangement is

four 21⁄2 percent taps, two above and two below the nominal. The primary voltage is typically less

than or equal to 15 kV and the secondary voltage is less than or equal to 600 V.

5­5The kVA ratings in design line 11 are 15 kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, 150

kVA, 225 kVA, 300 kVA, and 500 kVA. The shipments for this design line are primarily in the

kVA range inclusive of and between 225 kVA and 500 kVA; therefore, the Department selected the

300 kVA rating as the representative unit for analysis.

Design L ine 12

. Design line 12 represents three­phase, medium­voltage, ventilated dry­type

distribution transformers, ranging from 750 kVA to 2500 kVA. This design line parallels design

line 10, with a higher primary insulation level, 46 kV to 95 kV BIL. The typical tap arrangement is

four 21⁄2 percent taps, two above and two below the nominal. The primary voltage is typically less

than or equal to 15 kV and the secondary voltage is less than or equal to 600 V.

The r epresentative unit selected for this design line is a 1500 kVA transformer, as it is a

common rating in this size range and BIL rating, and it occurs in the middle of the kVA range

covered by this design line (750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA).

Design L ine 13

. As a further extension on the dry­type, three­phase, medium­voltage BIL

ranges, the Department analyzed 96 kV to 150 kV BIL, in a design line ranging from 225 kVA to

2500 kVA. The 225 kVA rating is considered to be the lowest kVA rating where one would expect

to see a unit with a BIL greater than 110 kV. The typical tap arrangement is four 21⁄2 percent taps,

two above and two below the nominal. The primary voltage is typically less than or equal to 35 kV

and the secondary voltage is less than or equal to 600 V.

This t hird set of dry­type, three­phase, medium­voltage distribution transformers spans a

smaller range of kVA ratings, 225 kVA to 2500 kVA. As most of the sales activity in this design

line occurs in the higher kVA ratings, the representative unit selected for design line 13 is a 2000

kVA transformer. This unit is a common rating in this size range, and occurs toward the high end of

the range covered by this design line (225 kVA, 300 kVA, 500 kVA, 750 kVA, 1000 kVA, 1500

kVA, 2000 kVA, and 2500 kVA).

In a ddition to the three product classes for dry­type, medium­voltage, three­phase

distribution transformers (for which there are five engineering design lines) presented in Table

5.2.1, there are three product classes for single­phase, dry­type, medium­voltage units. As discussed

in Chapter 3, the shipment volume for single­phase, dry­type, medium voltage transformers is very

low, and thus it does not warrant the level of effort involved in conducting analysis on these specific

units. The Department decided instead to scale the analysis findings from three­phase units to the

single­phase units by establishing the same energy conservation standard requirement on a ‘per

phase’ basis. In other words, the energy conservation standard requirements for a three­phase 1500

kVA medium­voltage dry­type would be scaled to be the same for a single­phase 500 kVA mediumvoltage dry­type. In this way, the Department was able to concentrate resources and improve the

accuracy in other, higher volume and more important distribution transformer product classes.

5.2.1 Summary o f Design Line Coverage

The f ollowing four tables summarize the coverage of each of the design lines in relation to

the various product classes and kVA ratings. The abbreviation DL stands for design line, and the

row in the table where the phrase “Rep Unit” appears indicates the kVA rating of the representative

5­6unit from that design line. The representative unit is the kVA rating which was analyzed in the

engineering and life­cycle cost analyses. For example, DL 1 stands for design line 1, spanning from

10 to 167 kVA liquid­type, single­phase. The label “Rep Unit” appears in row 50 kVA, indicating

that the 50 kVA is the representative unit for DL 1. Similarly, the representative unit for DL 2 is the

25 kVA unit.

There a re five liquid­immersed design lines, three single­phase and two three­phase, as

shown in Table 5.2.3. To capture any design differences between a single­phase pole and a padmounted transformer, the Department analyzed units in both DL 1 and DL 2, spanning the same

kVA ratings (10 kVA to 167 kVA). On the three­phase liquid­immersed side, there is no overlap

between those two design lines.

Table 5 .2.3 Liquid­Immersed Design Lines and Representative Units

Product Class 1

Liquid­Immersed,

Single­Phase 

### Product Class 2

Liquid­Immersed,

Three­Phase

kVA Rectang.

Tank Round

Tank 

### kVA Design

Lines

10 

### 15

15 

### 30

25 

### 45

37.5 

### 75

50 

### 112.5

75 

### 150

100 

### 225

167 

### 300

250 

### 500

333 

### 750

500 

### 1000

667 

### 1500

833 

### 2000

2500DL1DL2DL3 Rep Unit

Rep UnitDL4

Rep UnitDL5 Rep Unit Rep Unit

Table 5.2.4 presents product classes (abbreviated “PC”) for medium­voltage, single­phase,

dry­type units. As discussed in section 3.4, National Shipment Estimate, these units have an

extremely low shipment volume. All three product classes shown in Table 5.2.4 together represent

less than one­third of one percent of dry­type shipments on both a per­unit and an MVA­capacity

basis. Thus, the Department did not consider it appropriate to conduct analysis of any units from

these three product classes.

As a n alternative to investing time and resources analyzing these low­volume units, the

Department used the results from the medium­voltage, three­phase dry­type units (presented in

Table 5.2.6) and divided those findings by three, creating virtual (calculated) representative units

5­7(labeled as “Virtual RU” in the table) for these three product classes. The Department used the

representative units from design lines 9, 10, 11, 12, and 13. These virtual representative units are

shown in their respective rows, following the application of the quotient. For example, in the single

phase (20–45kV BIL) column, the representative unit from DL 9 is a three­phase 300 kVA unit, so

it scales to a single­phase, 100 kVA unit in Table 5.2.4.

Table 5 .2.4 Dry­Type, Medium­Voltage, Single­Phase Design Lines



### >



### ­



### ­



### ­



### ­3 

### Dry­Type, Medium­Voltage, Single­Phase



### kVA PC 5*

Low BIL

20­45kV PC 7

Med BIL

46­95kV PC 9

High BIL

96kV

15

25

37.5

50

75

100

167

250

333

500

667

833DL9/3

Virtual RUDL11/3

Virtual RUDL13/

Virtual RU Virtual RUDL10/3

Virtual RUDL12/3

Table 5.2.5 presents the product classes for the medium­voltage, three­phase, dry­type

distribution transformers and each of the design lines and respective representative units. For the

higher volume and larger range of kVA ratings, the Department used two separate design lines for

each, to maintain accuracy. However, for the very high BIL levels ( $ 96kV BIL), one design line

(DL 13) covers all the ratings from 225kVA to 2500kVA. Within DL 13, the Department did not

extrapolate the results of this unit to ratings of 150kVA and below because there were no shipments

at these ratings in the shipments analysis and it is very unlikely that they would be built.

5­8Table 5.2.5 Dry­Type, Medium­Voltage, Three­Phase Design Lines



### >



### ­



### ­



### ­



### ­



### ­



### ­ Dry­Type, Medium­Voltage, Three­Phase



### kVA PC 6

Low BIL

20­45kV PC 8

Med BIL

46­95kV PC 10

High BIL

96kV

15

30

45

75

112.5

150

225

300

500

750

1000

1500

2000

2500DL9DL11DL13 Rep Unit Rep UnitDL10DL12 Rep Unit Rep Unit

Rep Unit

5.2.2 Scaling R elationships in Transformer Manufacturing

The D epartment simplified the engineering analysis by creating design lines, selecting

representative units from these design lines, and scaling the results of the analysis on these

representative units within their respective design lines. This section briefly introduces the scaling

relationship the Department used to extrapolate the findings on the representative units to the other

kVA ratings. A more detailed discussion of the derivation of the 0.75 scaling rule is provided in

Appendix 5B.

The s caling formulae are mathematical relationships that exist between the kVA ratings and

the physical size, cost, and performance of transformers. The size­versus­performance relationships

arise from fundamental equations describing a transformer's voltage and kVA rating. For example,

when the kVA rating, voltage, and frequency are fixed, the product of the conductor current density,

core flux density, core cross­sectional area, and total conductor cross­sectional area is constant.

To i llustrate this point, consider a transformer with four fixed variables: frequency,

magnetic flux density, current density, and BIL rating. If one enlarges (or decreases) the kVA

rating, then the only parameters free to vary are the core cross­section and the core window area

through which the windings pass. Thus, to increase (or decrease) the kVA rating, the dimensions

for height, width, and depth of the core/coil assembly scale equally in all directions. Analysis of this

scaling relationship reveals that each of the linear dimensions varies as the ratio of kVA ratings to

the 1⁄4 power. Similarly, areas vary as the ratios of kVA ratings to the 1⁄2 power and volumes vary as

the ratio of the kVA ratings to the 3⁄4 or 0.75 power, hence the term "0.75 scaling rule." Application

of the 0.75 scaling rule assumes that the efficiency profile of a given transformer will have the same

5­9shape as the transformer being scaled. Table 5.2.6 depicts the most common scaling relationships in

transformers.

Table 5 .2.6 Common Scaling Relationships in Transformers

Parameter Being Scaled Relationship to k VA Rating

(varies w ith ratio of kVA x )

Weight (kVA

1 /kVA

0 ) 3/4

Cost (kVA

1 /kVA

0 ) 3/4

Length (kVA

1 /kVA

0 ) 1/4

Width (kVA

1 /kVA

0 ) 1/4

Height (kVA

1 /kVA

0 ) 1/4

Total Losses (kVA

1 /kVA

0 ) 3/4

No­load Losses (kVA

1 /kVA

0 ) 3/4

The following three relationships are true as the kVA rating increases or decreases, if the

type of transformer (liquid­immersed or dry­type, single­phase or three­phase), the primary voltage,

the core configuration, the core material, the core flux density, and the current density (amperes per

square inch of conductor cross­section) in both the primary and secondary windings are all held

constant:

1. The p hysical proportions are constant (same relative shape),

2. The e ddy loss proportion is essentially constant, and

3. The i nsulation space factor (voltage or BIL) is constant.

In p ractical applications, it is rare to find that all of the above are constant over even limited

ranges; however, over a range of one order of magnitude in both directions (e.g., from 50 kVA to 5

kVA or from 50 kVA to 500 kVA), the scaling rules shown in Table 5.2.6 can be used to establish

reasonable estimates of performance, dimensions, costs, and losses. In practice, these rules can be

applied over even wider ranges to estimate general performance levels. The Department’s

application of the 0.75 scaling rule in this analysis is always less than an order of magnitude.

S To i llustrate how the scaling laws are used, consider two transformers with kVA ratings of

0 and S

1 . The no­load losses (NL) and total losses (TL) of these two transformers would be

depicted as NL

0 and TL

0 , and NL

1 and TL

1 . Then the relationships between the NL and TL of the

two transformers could be shown as follows:

NL

1 = NL

0 × (S

1 / S

0 ) 0.75 Eq. 5.1

where:

NL

1 = no­load losses of transformer “1,”

5­10NL

0 = no­load l osses of transformer “0,”

S

1 = kVA rating o f transformer “1,” and

S

0 = kVA rating o f transformer “0.”

and

TL

1 = TL

0 × (S

1 / S

0 ) 0.75 Eq. 5.2

where:

TL

1 = total losses of transformer “1,” and

TL

0 = total losses of transformer “0.”

Equations 5 .1 and 5.2 can be manipulated algebraically to show that the load loss also varies

to the 0.75 power. Starting with the concept that total losses equals no­load losses plus load losses,

we can derive the relationship for load loss (LL), and show that it also scales to the 0.75 power.

Specifically:

LL

1 = TL

1 ­ NL

1 Eq. 5.3

where:

LL

1 = load losses of transformer “1”

Inserting t he TL

1 and NL

1 terms into this equation, we find:

LL

1 = (TL

0 × (S

1 / S

0 ) 0.75 )

­ (NL

0 × (S

1 / S

0 ) 0.75 ) Eq. 5.4

LL

1 = (TL

0 ­ NL

0 )× (S

1 / S

0 ) 0.75 Eq. 5.5

LL

1 = (LL

0 ) × (S

1 / S

0 ) 0.75 Eq. 5.6

Where:

LL

0 = load losses of transformer “0.”

5­11Thus, the 0.75 scaling rule can be applied to estimate the losses of a transformer, given the

losses and kVA rating of a reference (analyzed) unit. However, in order for this rule to be

applicable, the transformer type must be the same, and key parameters—such as the type of core

material, core flux density, and conductor current density in the high and low voltage

windings—must be fixed. Additionally, use of the 0.75 scaling rule assumes that the efficiency

profile of a given transformer will have the same shape as the transformer being scaled. A detailed

discussion on the derivation of the 0.75 scaling rule is provided in Appendix 5B.

The D epartment used the 0.75 scaling rule to scale the analysis findings on each of the

representative units within the 10 design lines to the 85 kVA ratings that were not analyzed. The

Department applied the scaling rule within the design lines in the national impact analysis (Chapter

10), where it calculated efficiency ratings for the 85 kVA ratings not analyzed.

5.3 TECHNICAL D ESIGN INPUTS

For a ll ten representative units, the engineering analysis explored the relationship between

the manufacturer selling prices and corresponding transformer efficiencies. For this analysis, the

Department contracted Optimized Program Service, Inc. (OPS) in Ohio, a software company

specializing in transformer design since 1969. Using a range of input parameters and material

prices, the OPS software produces a design. This design has specific information about the core and

coil, including physical characteristics, dimensions, material requirements and mechanical

clearances, as well as a complete electrical analysis of the final design. This optimized, practical

transformer design, the bill of materials, and an electrical analysis report contain sufficient

information for a manufacturer to build the unit. The software’s output is used to generate an

estimated cost of manufacturing materials and labor, which is then converted to a manufacturer

selling price by applying markups.

The e lectrical analysis report estimates the performance of the transformer design (including

efficiency) at 25 percent, 35 percent, 50 percent, 65 percent, 75 percent, 100 percent, 125 percent,

and 150 percent of nameplate load. The software output provides a clear understanding of the

relationship between cost and efficiency because it provides detailed data on design variances, as

well as a bill of materials, labor costs, and efficiency. The software does not capture retooling costs

associated with changing production designs for a specific manufacturer. In some cases, however,

the Department captured tooling costs associated with manufacturing mitered cores by applying

adders to the steel price.

One o f the inputs to the design software consisted of a range of what are known in the

industry as A and B evaluation combinations (see section 3.6, Total Ownership Cost Evaluation).

The combination of A and B input to the design software mimics a distribution transformer

purchase order. The A parameter represents a customer's present value of future losses in the

transformer core (no­load losses). The B value represents a customer's present value of future losses

in the windings (load losses). The B parameter is never larger than A, as this would imply a

specification for a transformer whose average load would be more than 100 percent of the

nameplate load. The A and B values take into account a range of factors that usually vary from

customer to customer.

5­12The A and B values are expressed in terms of dollars per watt of loss. The greater the values

of A and B, the greater the importance a customer attaches to the value of future transformer losses.

As A and B values increase, the customer places greater importance on reducing the watts of core

and winding losses, respectively, and so the customer chooses a more energy­efficient transformer.

The D epartment used broad ranging combinations of A and B evaluation formulae

(presented in Table 5.3.1 and Table 5.3.2) to create a complete set of efficiency levels for each

design option combination analyzed. The efficiency levels spanned from a low­first­cost unit to a

maximum technologically feasible (“max­tech”) design. For the low­first­cost design, the A and B

evaluation values were both $0/watt, indicating that the customer does not attach any financial value

to future losses in the core or coil of the transformer. For the maximum technologically feasible

design, the A and B evaluation values were very high, pushing the software to design at the highest

efficiencies achievable.

The D epartment created its combinations of A and B evaluation formulae combining two

techniques to ensure there were sufficient designs in the database for the analysis. The first

technique was to create, as in the advance notice of proposed rulemaking (ANOPR), a ‘grid’ of A

and B combinations. The ‘grid’ technique involved increasing the value of A by a step value, and

then increasing the B value from zero to that value of A, using a different step value. Thus, if A had

incremental steps of $0.25 and B had steps of $0.20, the combinations would work as follows:

($0.00, $0.00), ($0.25, $0.00), ($0.25, $0.20), ($0.50, $0.00), ($0.50, $0.20), ($0.50, $0.40), ($0.75,

$0.00), and so on. Table 5.3.1 presents the ranges and incremental steps for the A and B

combinations used in the three grids.

Table 5 .3.1 A and B Grid Combinations used by Software to Generate Design Database

Grid

Number A v alues

and increments B v alues

and increments Resultant # of

(A, B) combinations

1 $0 t o $2 by 0.25 steps $0 t o $2 by 0.20 steps 47

2 $2.50 t o $8 by 0.50 steps $0 t o $8 by 0.40 steps 157

3 $9 t o $16 by 1.00 steps $3 t o $8 by 0.50 steps 85

The second technique for generating A and B evaluation formulae in the engineering

analysis was new for the notice of proposed rulemaking (NOPR). The Department understands that

the ratio of A to B represents an implicit loading for the transformer. Therefore, the Department

created a set of (A, B) values in which the B is calculated from the A. The B term is calculated as

the A times the percent load squared. In other words, if A equals $1 and DOE is interested in

calculating the appropriate B for a 50 percent root­mean­square (RMS) load, then it would be $1

times (0.50)^2, or $0.25. Thus, the combination of ($1.00, $0.25) represents approximately a 50

percent RMS load. As with the “grid,” the A values increased with a step function, and B values

were calculated as fractions of A so that the ratio of A to B encompassed the RMS loading points

that were identified in the Department’s loading analysis (i.e., 35 percent and 50 percent). Calling

this approach the “fan,” DOE calculated the B values for each A at the following RMS loading

points: 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, 30 percent, 35 percent, 40 percent,

45 percent, 50 percent, 55 percent, and 60 percent. Table 5.3.2 presents the range of the two fan

combinations used in the NOPR.

5­13Table 5.3.2 A and B Fan Combinations used by Software to Generate Design Database

Fan A v alues B v alues Resultant # of

Number and increments and increments (A,B) c ombinations

1 $0 t o $2 by 0.50 steps 5% t o 60% implicit loading by 5% steps 47

2 $3 t o $16 by 1.00 steps 5% t o 60% implicit loading by 5% steps 182

When used together, these two techniques created a broad spectrum of A and B

combinations as inputs to the OPS software. Figure 5.3.1 illustrates the coverage of designs for the

518 A and B combinations. Each of these A and B combinations were used with each combination

of core steel and winding combination analyzed for each representative transformer studied.

Figure 5.3.1 A and B Combination Software Inputs used in the Engineering Analysis

Occasionally, t he design software generated the same transformer design for two different A

and B combinations, creating duplicate designs in the engineering analysis database. These

duplicate designs were removed before the engineering database was imported into the LCC

analysis.

The D epartment understands that there are many ways to build a transformer, even with

constant kVA and voltage ratings. For instance, manufacturers can vary the core steels (e.g., M2,

M3, M6), the winding materials (aluminum or copper), and core configurations (shell or core­type).

Within each of the design lines discussed in the sections starting at 5.3.1, the Department provides

tables listing the design option combinations that it used to analyze each of the representative units.

5­14Depending on customer needs, the cost of materials, the capital equipment in their facility, and the

skills of their labor force, manufacturers make decisions on how to manufacture a given transformer

using different core configurations, core steels, and winding materials. To capture this variation in

designs, DOE analyzed the 10 representative units using 5–11 different design option combinations

of core type, core steel, and winding material. As discussed in the technology assessment (see

Chapter 3), core steel is produced in a range of qualities (from an efficiency perspective). M2 core

steel is oriented grain silicon steel and has thin laminations, and consequently has very low losses.

M43 core steel is non­oriented grain silicon steel and is rolled in much thicker laminations, thus

contributing to higher core losses. Table 5.3.3 lists all the steel types used in the analysis, and

properties associated with these steels. Each steel grade provides the nominal thickness and core

losses per pound of steel, under a specified typical magnetic flux density, measured in Tesla.

Table 5 .3.3 Core Steel Grades, Thicknesses and Associated Losses

Steel

Grade Nominal

T hickness

inches Core L oss at 60 Hz

Watts per Pound at

magnetic flux density * Notes / Remarks

M43 0.0185 2.10 W atts/lb at 1.5 T Non­oriented g rain silicon steel

M36 0.0185 2.00 W atts/lb at 1.5 T Non­oriented g rain silicon steel

M19 0.0185 1.65 W atts/lb at 1.5 T Non­oriented g rain silicon steel

M6 0.014 0.66 W atts/lb at 1.5 T

0.94 Watts/lb at 1.7 T Grain­oriented s ilicon steel

M5 0.012 0.53 W atts/lb at 1.5 T

0.83 Watts/lb at 1.7 T Grain­oriented s ilicon steel

M4 0.011 0.51 W atts/lb at 1.5 T

0.74 Watts/lb at 1.7 T Grain­oriented s ilicon steel

M3 0.009 0.45 W atts/lb at 1.5 T

0.70 Watts/lb at 1.7 T Grain­oriented s ilicon steel

M2 0.007 0.41 W atts/lb at 1.5 T Grain­oriented s ilicon steel

H­0 D R 0.009 0.60 W atts/lb at 1.7 T “Domain­refined, h igh permeability” grade

silicon steel

SA1 0.001 0.08 W atts/lb at 1.3 T Amorphous c ore steel (silicon and boron); flux

density limitation ­ testing at 1.3 T

ZDMH 0.009 0.34 W atts/lb at 1.5 T

0.46 Watts/lb at 1.7 T Imported s ilicon steel, magnetic domainrefined by mechanical process

* Watts o f loss per pound of core steel are only comparable at the same magnetic flux density (measured in Tesla)

In addition to selecting a core steel, the manufacturer’s selection of a core design may also

contribute to the overall efficiency of a transformer. A transformer facility may be optimized to

work around one or two core configurations. Table 5.3.4 provides a list of all the core

configurations used for each of the 10 design lines. The Department selected these configurations,

in combination with the range of core steels and winding materials, to represent the most common

5­15construction methods for these kVA ratings in the US market. Note that, for design lines 2, 3, and

9, the Department analyzed two different core construction configurations.

Table 5 .3.4 Core Configurations Used in Each Design Line

Design Line # P hases Core C onfigurations Used in the Engineering Analysis

DL 1 1 Wound c ore ­ distributed gap, shell­type

DL 2 1 Wound c ore ­ distributed gap, shell­type or core­type

DL 3 1 Wound c ore ­ distributed gap, shell­type or core­type

DL 4 3 Wound c ore ­ distributed gap, 5­leg

DL 5 3 Wound c ore ­ distributed gap, 5­leg

DL 9 3 Stacked, butt­lap or mitered joint, 3­leg

DL 10 3 Stacked, c ruciform, mitered joint, 3­leg

DL 11 3 Stacked, m itered joint, 3­leg

DL 12 3 Stacked, c ruciform, mitered joint, 3­leg

DL 13 3 Stacked, c ruciform, mitered joint, 3­leg

For the single­phase representative units, the configurations used are either core­type or

shell­type. This applies whether the core consists of stacked or wound laminations of core steel.

For wound cores, manufacturers generally employ a technique known as ‘distributed gap.’ This

means that each lamination of core steel wound around the form will have a start and finish point

(the ‘gap’), staggered with respect to the previous and the next lamination. Distributed gap core

construction techniques are used to minimize the performance impact of the lamination joint gaps

(reducing the exciting current) and, by locating inside the coil window, reduce the transformer’s

operating sound level. Figure 5.3.2 illustrates the two types of single­phase core construction.

Figure 5.3.2 Graphic of Single­Phase Core Configurations

Three­phase t ransformers can have three­legged, four­legged, five­legged, or Evans cores.

In the engineering analysis, the Department considered the three­legged construction techniques for

the three­phase dry­types and five­legged construction for the three­phase liquid­immersed

transformers. Figure 5.3.3 below illustrates the difference between the three­legged and the fivelegged core construction techniques. A three­legged core is assembled from stacked laminations,

the joints of which can be butt­lapped or mitered. Where there is an economic need to reduce core

losses, particularly in keeping with the use of more efficient grades of core steel (M2 or M3), the

5­16mitered core tends to be selected. The Department recognizes that there are a variety of approaches

to mitered core construction: “scrapless T­mitering,” “full­mitering,” and “step­mitering.” The

Department modeled full­mitered cores.

Figure 5.3.3 Graphic of Three­phase Core Configurations

For larger kVA ratings, design economics may cause the selection of a cruciform core

section, where multiple lamination widths are stacked in increasing and then decreasing widths to

create a circular core form (or “log”) around which the windings are placed. Figure 5.3.4 illustrates

the cruciform core by showing a cross­section. This figure shows four different widths of steel

being used, but there can be fewer or more widths, depending on the design. By using a core

configuration that better follows the contours of the windings, losses are again reduced, resulting in

a more efficient transformer. The use of the three­legged core usually depends on the primary

winding being delta­connected. If the primary winding is wye­connected, as is frequently the case

for pad­mounted transformers used in underground distribution, the core configuration needs to be

four­legged or five­legged.

Figure 5.3.4 C r u c i f o r m C o r e

Cross­Section

The five­legged core is assembled from four wound­core loops, and is the common

configuration for liquid­filled, three­phase distribution transformers having a wye­wye voltage

connection. Again, this occurs for pad­mounted transformers used in underground distribution. The

individual core loops have distributed gaps, as explained for single­phase, wound­core transformers.

5­17Finally, for liquid­immersed distribution transformers, DOE studied the differences between

mineral oil cooled units and less­flammable cooled units. DOE understands that the IEEE standard

C57.12.80 divides less­flammable liquid­immersed transformers into two groups: KNAN (which

have an insulating liquid with a fire point greater than 300 degrees Celsius) and LNAN (which have

an insulating liquid with no measurable fire point). The fire point for mineral oil is approximately

175 degrees Celsius, and therefore this type of transformer is not used inside buildings or in areas

designated as hazardous. While industry has a specification for KNAN for a certain degree of fire

protection or LNAN for users who prefer an extra measure of safety, DOE will continue to refer to

both KNAN and LNAN using the phrase ‘less­flammable’ as that was the term used by stakeholders

when they were commenting on DOE’s notice of proposed rulemaking.

DOE u nderstands that the viscosity of the insulating liquid can have a slight impact on the

efficiency of a transformer. When the viscosity is higher than mineral oil, transformer designers

must make slightly larger cooling ducts to permit an easier flow of the fluid. Larger ducts result in

larger physical size of the winding assembly, greater mean turn of the conductor, and therefore

contribute to a slightly higher load loss. Thus, a particular efficiency level can be more difficult to

reach when using a cooling medium with viscosity higher than that of mineral oil.

For t he KNAN transformers (i.e., those with a fire point of 300 degrees or greater), DOE is

not aware of any viscosity differences with mineral oil that might impede designs or make efficiency

levels significantly more difficult to reach. For LNAN transformers (i.e., those with no fire point),

DOE understands that the viscosity under usual operating conditions is slightly greater than that of

mineral oil, which would require design engineers to increase the duct size, leading to a marginal

impact on efficiency. However, DOE has not received comment on this issue and does not believe

this marginal impact is sufficiently large enough to warrant separate regulatory treatment.

5.3.1 Design L ine 1 Representative Unit

Design l ine 1 (DL 1) represents rectangular­tank, liquid­immersed, single­phase distribution

transformers, ranging from 10 kVA to 167 kVA. The representative unit selected for this design

line is a 50kVA pad­mounted unit. The following are the technical specifications that constitute

input parameters to the OPS design software:

KVA: 5 0 (liquid­immersed, rectangular­tank)

Primary: 14400 Volts at 60 Hz

Secondary: 240/120V

T Rise: 65°C

Ambient: 20°C

Winding Configuration: Lo­Hi­Lo (Shell­Type)

Core: Wound core ­ distributed gap

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 1.0–3.5 percent

For D L 1, DOE selected eight construction combinations (called “design option

combinations”), based on input from manufacturers and other technical experts. The core selected

was shell­type, because the application is for a pad­mounted unit, and this shape is well suited to a

rectangular tank. With the exception of the max tech/high efficiency designs, DOE selected eight

5­18design option combinations to represent the most common construction practices for this

representative unit.

Table 5 .3.5 Design Option Combinations for the Representative Unit from Design Line 1

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) Shell

­ DG* Wound Core

M6 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M3 Al ( wire) Al ( strip) Shell

­ DG Wound Core

M3 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

ZDMH Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

SA1 ( Amorphous) Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

*DG ­ Distributed gap wound core construction, where the core laminations are wound in such a way that the gap

between the start and finish of a lamination is staggered in the cross­section of the core.

The Department analyzed each of the eight design option combinations using the matrix of

A and B values described in Tables 5.3.1 and 5.3.2, creating 3,926 designs (after removing nonfeasible designs).

5.3.2 Design L ine 2 Representative Unit

Design l ine 2 (DL 2) represents round­tank, liquid­immersed, single­phase distribution

transformers, ranging from 10 kVA to 167 kVA. The representative unit selected for this design

line is a 25kVA pole­mounted unit. The following are the technical specifications that constitute

input parameters to the OPS design software:

KVA: 2 5 (liquid­immersed, round­tank)

Primary: 14400 Volts at 60 Hz (125 kV BIL)

Secondary: 120/240V

T Rise: 65°C

Ambient: 20°C

Winding Configuration: Lo­Hi­Lo (Shell­Type), Lo­Hi (Core­Type, for amorphous core)

Core: Wound core ­ distributed gap

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 1.0–3.5 percent

For D L 2, DOE selected 10 design option combinations, based on input from manufacturers

and other technical experts. With the exception of the max tech/high­efficiency designs, DOE

selected these design option combinations to represent the most common construction practices for

the representative unit.

5­19Table 5.3.6 Design Option Combinations for the Representative Unit from Design Line 2

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) Shell

­ DG Wound Core

M6 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M4 Al ( wire) Al ( strip) Shell

­ DG Wound Core

M4 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M3 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M3 Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

ZDMH Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

SA1 ( Amorphous) Cu ( wire) Cu ( strip) Core

­ DG Wound Core

The Department analyzed each of the 10 design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 5,159 designs (after removing nonfeasible designs).

5.3.3 Design L ine 3 Representative Unit

Design l ine 3 (DL 3) represents round­tank, liquid­immersed, single­phase distribution

transformers, ranging from 250 kVA to 833 kVA. The representative unit selected for this design

line is a 500kVA round­tank transformer. The following are the technical specifications which

constitute input parameters to the OPS design software:

KVA: 5 00 (liquid­immersed, round­tank)

Primary: 14400 Volts at 60 HZ (150kV BIL)

Secondary: 277 Volts

T Rise: 65°C

Ambient: 20°C

Winding Configuration: Lo­Hi­Lo (Shell­Type), Lo­Hi (Core­Type, for amorphous core)

Core: Wound core ­ distributed gap

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 2.5–5.75 percent

For D L 3, the Department selected seven design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE chose design option combinations to

represent the most common construction practice for this representative unit.

5­20Table 5.3.7 Design Option Combinations for the Representative Unit from Design Line 3

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) Shell

­ DG Wound Core

M4 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M3 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Al ( strip) Shell

­ DG Wound Core

M2 Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

ZDMH Cu ( wire) Cu ( strip) Shell

­ DG Wound Core

SA1 ( Amorphous) Cu ( wire) Cu ( strip) Core­ DG W ound Core

The Department analyzed each of the seven design option combinations using the matrix of

A and B values described in Tables 5.3.1 and 5.3.2, creating 2,929 designs (after removing nonfeasible designs).

5.3.4 Design L ine 4 Representative Unit

Design l ine 4 (DL 4) represents rectangular tank, liquid­immersed, three­phase distribution

transformers, ranging from 15 kVA to 500 kVA. The representative unit selected for this design

line is a 150kVA transformer. The following are the technical specifications that constitute input

parameters to the OPS design software:

KVA: 1 50 (liquid­immersed, pad mount)

Primary: 12470Y/7200 Volts at 60 HZ (95kV BIL)

Secondary: 208Y/120 Volts

T Rise: 65°C

Ambient: 20°C

Terminal Configuration: ANSI/IEEE C57.12.26, Loop Feed

Winding Configuration: Lo­Hi (Core­Type)

Core: Wound core ­ distributed gap, 5­leg

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 1.5–3.0 percent

For D L 4, DOE selected seven design option combinations of core steel and winding types

based on input from manufacturers and other technical experts. With the exception of the max

tech/high efficiency designs, DOE selected these design option combinations to represent the most

common construction practice for the representative unit.

5­21Table 5.3.8 Design Option Combinations for the Representative Unit from Design Line 4

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) 5­Leg D G Core

M4 Al ( wire) Al ( strip) 5­Leg D G Core

M3 Cu ( wire) Al ( strip) 5­Leg D G Core

M2 Cu ( wire) Al ( strip) 5­Leg D G Core

M2 Cu ( wire) Cu ( strip) 5­Leg D G Core

ZDMH­price 1 Cu ( wire) Cu ( strip) 5­Leg D G Core

SA1 ( Amorphous) Cu ( wire) Cu ( strip) 5­Leg D G Core

The Department analyzed each of the seven design option combinations using the matrix of

A and B values described in Tables 5.3.1 and 5.3.2, creating 3,549 designs (after removing nonfeasible designs).

5.3.5 Design L ine 5 Representative Unit

Design l ine 5 (DL 5) represents rectangular tank, liquid­immersed, three­phase distribution

transformers, ranging from 750 kVA to 2500 kVA. The representative unit selected for this design

line is a 1500kVA transformer. The following are the technical specifications that constitute input

parameters to the OPS design software:

KVA: 1 500 (liquid­immersed, pad mount)

Primary: 24940GrdY/14400 Volts (125kV BIL)

Secondary: 480Y/277 Volts

T Rise: 65°C

Ambient: 20°C

Terminal Configuration: ANSI/IEEE C57.12.26, Loop Feed

Winding Configuration: Lo­Hi (Core­Type)

Core: Wound core ­ distributed gap, 5­leg

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 4.5­7.0 percent

For D L 5, the Department selected seven design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practices for the representative unit.

5­22Table 5.3.9 Design Option Combinations for the Representative Unit from Design Line 5

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M4 Al ( wire) Al ( strip) 5­Leg D G Core

M4 Cu ( wire) Al ( strip) 5­Leg D G Core

M3 Cu ( wire) Al ( strip) 5­Leg D G Core

M2 Cu ( wire) Al ( strip) 5­Leg D G Core

M2 Cu ( wire) Cu ( strip) 5­Leg D G Core

ZDMH Cu ( wire) Cu ( strip) 5­Leg D G Core

SA1 ( Amorphous) Cu ( wire) Cu ( strip) 5­Leg D G Core

The Department analyzed each of the seven design option combinations using the matrix of

A and B values described in Tables 5.3.1 and 5.3.2, creating 3,350 designs (after removing nonfeasible designs).

5.3.6 Design L ine 9 Representative Unit

Design l ine 9 (DL 9) represents ventilated dry­type, three­phase, medium­voltage

distribution transformers with a 20–45kV BIL, ranging from 15 kVA to 500 kVA. The

representative unit selected for this design line is a 300 kVA transformer. The following are the

technical specifications that constitute input parameters to the OPS design software:

KVA: 3 00 (dry­type)

Phases: Three

Primary: 4160V at 60 Hz (45 kV BIL) Delta Connected

Secondary: 480Y/277 Volts

T Rise: 150°C

Ambient: 20°C

Winding Configuration: Lo­Hi

Core: Stacked, butt­lap; Stacked, mitered

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 3.0–6.0 percent

For D L 9, the Department selected five design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practice for the representative unit.

5­23Table 5.3.10 Design Option Combinations for the Representative Unit from Design Line 9

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6, 2 9 gauge Al ( wire) Al ( wire) 3­Leg S tacked Buttlap

M6, 2 9 gauge Cu ( wire) Cu ( wire) 3­Leg S tacked Full Miter**

M5 Al ( wire) Al ( wire) 3­Leg S tacked Full Miter

M3 Cu ( wire) Al ( strip) 3­Leg S tacked Full Miter

H­O D R* Cu ( wire) Cu ( strip) 3­Leg S tacked Full Miter

* H­O D R is a domain­refined, high permeability core steel, and represents the max tech for dry­type units.

** Full M iters are not step­miters, but are mitered joints for all three legs. These cores are stacked three by three.

The Department analyzed each of the five design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 2,324 designs (after removing nonfeasible designs).

5.3.7 Design L ine 10 Representative Unit

Design l ine 10 (DL 10) represents dry­type, three­phase, medium­voltage distribution

transformers with a 20–45kV BIL, ranging from 750 kVA to 2500 kVA. The representative unit

selected for this design line is a 1500 kVA transformer. The following are the technical

specifications that constitute input parameters to the OPS design software:

KVA: 1 500 (dry­type)

Phases: Three

Primary: 4160V at 60 Hz (45 kV BIL)

Secondary: 480Y/277 Volts

T Rise: 150°C

Ambient: 20°C

Winding Configuration: Lo­Hi

Core: Stacked, cruciform, mitered joint

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 4.0­6.0 percent

For D L 10, the Department selected five design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practice for the representative unit.

5­24Table 5.3.11 Design Option Combinations for the Representative Unit from Design Line 10

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) 3­Leg M itered Cruciform

M6 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

M4 Cu ( wire) Al ( strip) 3­Leg M itered Cruciform

M3 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

H­O D R* Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

* H­O D R is a domain­refined, high permeability core steel, and represents the max tech for dry­type units.

The Department analyzed each of the five design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 1,866 designs (after removing nonfeasible designs).

5.3.8 Design L ine 11 Representative Unit

Design l ine 11 (DL 11) represents dry­type, three­phase, medium­voltage distribution

transformers with a 46–95kV BIL, ranging from 15 kVA to 500 kVA. The representative unit

selected for this design line is a 300 kVA transformer. The following are the technical

specifications that constitute input parameters to the OPS design software:

KVA: 3 00 (dry­type)

Phases: Three

Primary: 12470 Volts at 60 Hz (95 kV BIL)

Secondary: 480Y/277 Volts

T Rise: 150°C

Ambient: 20°C

Winding Configuration: Lo­Hi

Core: Stacked, mitered joint

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 3.0­7.0 percent

For D L 11, the Department selected five design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practice for the representative unit.

5­25Table 5.3.12 Design Option Combinations for the Representative Unit from Design Line 11

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) 3­Leg S tacked Full Miter**

M6 Cu ( wire) Cu ( strip) 3­Leg S tacked Full Miter

M4 Cu ( wire) Al ( strip) 3­Leg S tacked Full Miter

M3 Cu ( wire) Cu ( strip) 3­Leg S tacked Full Miter

H­O D R* Cu ( wire) Cu ( strip) 3­Leg S tacked Full Miter

* H­O D R is a domain­refined, high permeability core steel, and represents the max tech for dry­type units.

** Full M iters are not step­miters, but are mitered joints for all three legs. These cores are stacked three by three.

The Department analyzed each of the five design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 1,268 designs (after removing nonfeasible designs).

5.3.9 Design L ine 12 Representative Unit

Design l ine 12 (DL 12) represents dry­type, three­phase, medium­voltage distribution

transformers with a 46–95kV BIL, ranging from 750 kVA to 2500 kVA. The representative unit

selected for this design line is a 1500 kVA transformer. The following are the technical

specifications that constitute input parameters to the OPS design software:

KVA: 1 500 (dry­type)

Phases: Three

Primary: 12470 Volts at 60 Hz (95 kV BIL)

Secondary: 480Y/277 Volts

T Rise: 150°C

Ambient: 20°C

Winding Configuration: Lo­Hi

Core: Stacked, cruciform, mitered joint

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 4.0–7.0 percent

For D L 12, the Department selected five design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practice for the representative unit.

5­26Table 5.3.13 Design Option Combinations for the Representative Unit from Design Line 12

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) 3­Leg M itered Cruciform

M6 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

M4 Cu ( wire) Al ( strip) 3­Leg M itered Cruciform

M3 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

H­O D R* Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

* H­O D R is a domain­refined, high permeability core steel, and represents the max tech for dry­type units.

The Department analyzed each of the five design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 2,343 designs (after removing nonfeasible designs).

5.3.10 Design L ine 13 Representative Unit

Design l ine 13 (DL 13) represents dry­type, three­phase, medium­voltage distribution

transformers with a $ 96kV BIL, ranging from 225 kVA to 2500 kVA. The representative unit

selected for this design line is a 2000 kVA transformer. The following are the technical

specifications that constitute input parameters to the OPS design software:

KVA: 2 000 (dry­type)

Phases: Three

Primary: 12470 Volts at 60 Hz (125 kV BIL)

Secondary: 480Y/277 Volts

T Rise: 150°C

Ambient: 20°C

Winding Configuration: Lo­Hi

Core: Stacked, cruciform, mitered joint

Taps: Four 21⁄2 percent, two above and two below the nominal

Impedance Range: 4.0–7.0 percent

For D L 13, the Department selected five design option combinations of core steel and

winding material, based on input from manufacturers and other technical experts. With the

exception of the max tech/high­efficiency designs, DOE selected these design option combinations

to represent the most common construction practice for the representative unit.

5­27Direct

Labor Direct

Material Overhead Selling General &

Admin. R & D Interest Full Cost of Product Table 5.3.14 Design Option Combinations for the Representative Unit from Design Line 13

Core Material High­Voltage

C onductor Low­Voltage

C onductor Core D esign Type

M6 Al ( wire) Al ( strip) 3­Leg M itered Cruciform

M6 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

M4 Cu ( wire) Al ( strip) 3­Leg M itered Cruciform

M3 Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

H­O D R* Cu ( wire) Cu ( strip) 3­Leg M itered Cruciform

* H­O D R is a domain­refined, high permeability core steel, and represents the max tech for dry­type units.

The Department analyzed each of the five design option combinations using the matrix of A

and B values described in Tables 5.3.1 and 5.3.2, creating 2,419 designs (after removing nonfeasible designs).

5.4 MATERIAL A ND LABOR INPUTS

The D epartment uses a standard method of cost accounting to determine the costs associated

with manufacturing. This methodology is illustrated in Figure 5.4.1, where production costs and

non­production costs are combined to determine the manufacturer’s selling price of a product.

1

­

­

­

­ Direct

Labor Direct

Material Overhead Selling General &

Admin. R & D Interest

Indirect Labor Full Production Cost Non­Production Cost

Indirect Material

Maintenance

Depreciation

Taxes

Insurance related

to assets Mkt. research

Advertising

POS promotion

Sales person

salary + travel

+ commission

Logistics

Warehousing

Delivery

Record

keeping

Order entry/

processing Costs of

service &

staff units

General

corporate

costs

­ comp. etc. Costs

associated

with efforts

to find new

or improved

products or

production

processes Costs

of

borrowing

funds Full Cost of Product

Code

compliance

Modernization Cust. service

1 Tax Reform Act of 1986, essentially, requires companies to measure cost of goods sold as the full production cost of the goods sold.

Figure 5.4.1 Standard Method of Cost Accounting for Standards Rulemaking

5­28The full production cost and the non­production cost equal the manufacturer’s selling price

of the product. Full production cost is a combination of direct labor, direct materials, and overhead.

The overhead contributing to full production cost includes indirect labor, indirect material,

maintenance, depreciation, taxes, and insurance related to company assets. Non­production cost

includes the cost of selling (market research, advertising, sales representatives, logistics), general

and administrative costs, research and development (R&D), interest payments, and profit factor (not

shown). Because profit factor is included in the non­production cost, the sum of production and

non­production costs is an estimate of the manufacturer’s selling price.

The D epartment developed estimates of the costs listed in Figure 5.4.1 from the U.S.

Industry Census Data Reports for 1992 and 1997, manufacturer interviews, and Securities and

Exchange Commission (SEC) 10­K reports for ACME Electric Corporation, Powell Industries, Inc.,

Magnetek, Inc., and Hammond Manufacturing Company Limited. It then refined these estimates

through meetings and dialogue with transformer manufacturers in early 2002. The following

markups resulted:

• Scrap a nd handling factor: 2.5 percent markup. This markup applies to variable materials

(e.g., core steel, windings, insulation). It accounts for the handling of material (loading into

assembly or winding equipment) and the scrap material that cannot be used in the production

of a finished transformer (e.g., lengths of wire too short to wind, trimmed core steel).

• Mitered s crap factor: 4.0 percent markup. An additional scrap markup applies to steel used

in full­mitered cores. This markup represents material cut from the notch in the yoke.

• Factory o verhead: 12.5 percent markup. Factory overhead includes all the indirect costs

associated with production, indirect materials and energy use (e.g., annealing furnace), taxes,

and insurance. The Department only applied factory overhead to the direct material

production costs.

• Non­production: 2 5 percent markup. This markup reflects costs including selling, general

and administrative, R&D, interest payments, and profit factor. The Department applied the

non­production markup to the sum of direct material, direct labor, and factory overhead.

The f ollowing example shows how the Department applied the markups to the materials, and

how it determined the manufacturer selling price. Consider a 300kVA 45kV BIL three­phase, drytype transformer designed with a $1.50 A and a $0.30 B. This design has $2,785 of materials,

including M6 core steel, copper primary and secondary windings, and all the transformer hardware.

There are approximately 27 hours of labor involved in manufacturing this design, resulting in a

labor cost of $1,167. The factory overhead on this design is $348, as it is only applied to the

material cost (i.e., 12.5 percent of $2,785). The non­production cost is $1,075, since the 25 percent

is applied to the material, labor, and factory overhead costs (i.e., 25 percent of $2,785 + $1,167 +

$348). Thus, in total, DOE estimates this 300kVA three­phase transformer to have a manufacturer

selling price of $5,375.

5­295.4.1 Material P rices

The D epartment received considerable input from manufacturers concerning recent increases

in the cost of materials, particularly core steel. The Department used prices of core steel, conductor,

mineral oil, insulation, and other materials as an input to the transformer design software used for

the engineering analysis. As the price of one material increases or decreases relative to the other

materials, the software will modify its design and increase or decrease the amount of that material

while balancing other design parameters, creating a cost­optimized transformer. Material pricing is

also critical because the manufacturer’s selling prices calculated in the engineering analysis are

based on a bill of materials that includes specifications for pounds of steel, pounds of conductor,

gallons of mineral oil, tank dimensions, and so on. Therefore, as material prices increase, so will

the manufacturer’s selling price. Furthermore, as discussed in Chapter 3, energy­efficient

transformers tend to incorporate more materials (e.g., pounds of core steel, pounds of conductor),

making the impact of more expensive materials even more significant at higher efficiencies.

The D epartment contracted OPS to develop material price estimates for the engineering

analysis. OPS used data from their own records as well as data provided by transformer

manufacturers and material suppliers and wholesalers. Although not all transformer manufacturers

pay the same amount per pound for electrical­grade steels, due to varied contract negotiations, these

prices are intended to be representative of a standard quantity order for a medium­ to large­scale

U.S. transformer m anufacturer. The Department conducted the engineering analysis using two

material price scenarios: 1) a five­year average of the material prices (in constant 2006$) from

2002, 2003, 2004, 2005 and 2006 and 2) a current material price sensitivity, using the average

annual material prices from 2006. OPS gathered both the five­year average and the 2006 material

prices in the same manner, providing consistency to the two pricing scenarios used in the

engineering analysis. The consideration of a second set of material prices in the engineering

analysis was directly in response to comments received, during the review of the NOPR analysis,

indicating that material prices are increasing rapidly and the historical lows of recent past were

unlikely to be experienced again. The results of the 2006 material price engineering analysis are

presented in Appendix 5C.

The D epartment noted that the most critical material input to a distribution transformer,

electrical core steel, had increased significantly for some M­grades between the five­year average

price and 2006 sensitivity (see Table 5.4.1). For this reason, the Department researched the grainoriented electrical steel market to gain a better understanding of the main players and some of the

factors influencing this significant price increase (see Appendix 3A).

In t he LCC analysis (Chapter 8), the Department presents results on its sensitivity analyses

conducted on various LCC inputs, which included material prices. In Chapter 8, the 2006 material

price scenario is referred to as the “high” price scenario and the 2002–2006 average price scenario is

called the “medium” price scenario. The Department then developed a hypothetical "low" price

scenario to establish a lower bound for the LCC sensitivity analysis. It based the low price scenario

on material prices in 2002 (the calender year with the lowest $/pound for M6 core steel) and reduced

all the material prices in that year by 15 percent. These material prices can be found in the material

price tables presented in this section. The resulting low­price scenario manufacturer selling prices

are provided in the LCC spreadsheets.

5­305.4.2 Material I nputs to the Design Software—Liquid­Immersed

Table 5 .4.1 presents the material prices for a typical liquid­immersed transformer

manufacturer in 2006, the hypothetical low material prices (for the LCC material price sensitivity,

presented in Chapter 8), and the 2002–2006 five­year average prices (all in constant 2006$). The

highlighted columns are the prices that DOE used in the engineering analysis.

Table 5 .4.1 Manufacturer’s Material Prices for Liquid­Immersed Design Lines

Material 2006

$

/lb. 2002

­ 15%

2006$/

lb. 5­yr

Avg.

2006$/

lb. 2006

2006$/

lb. 2005

2006$/

lb. 2004

2006$/

lb. 2003

2006$/

lb. 2002

2006$/

lb.

M2 core steel $1.66 $0.81 $1.16 $1.66 $1.23 $1.01 $0.95 $0.96

M3 c ore steel $1.62 $0.70 $1.06 $1.62 $1.16 $0.85 $0.84 $0.82

M4 c ore steel $1.59 $0.69 $1.02 $1.59 $1.12 $0.80 $0.77 $0.81

M6 c ore steel $1.40 $0.62 $0.92 $1.40 $0.98 $0.73 $0.74 $0.72

ZDMH ( mechanically­scribed core steel) $1.75 $1.33 $1.63 $1.75 $1.70 $1.59 $1.53 $1.56

SA1 ( amorphous) ­ finished core, volume

production $2.20 $1.82 $2.14 $2.20 $2.06 $2.20 $2.13 $2.14

Copper w ire, formvar, round #10­20 $4.99 $1.20 $2.58 $4.99 $2.70 $2.23 $1.59 $1.42

Copper w ire, enameled, round #7­10

flattened $5.28 $1.17 $2.62 $5.28 $2.69 $2.17 $1.56 $1.38

Copper w ire, enameled, rectangular sizes $4.45 $1.27 $2.80 $4.45 $3.22 $2.66 $2.17 $1.49

Aluminum w ire, formvar, round #9­17 $1.68 $1.24 $1.53 $1.68 $1.36 $1.62 $1.52 $1.46

Aluminum w ire, formvar, round #7­10 $1.71 $1.25 $1.55 $1.71 $1.38 $1.63 $1.54 $1.47

Copper s trip, thickness range 0.020­0.045 $3.15 $2.01 $2.69 $3.15 $2.87 $2.65 $2.41 $2.36

Copper s trip, thickness range 0.030­0.060 $3.05 $1.93 $2.61 $3.05 $2.80 $2.59 $2.31 $2.27

Aluminum s trip, thickness range 0.020­

0.045 $2.01 $1.40 $1.70 $2.01 $1.45 $1.70 $1.70 $1.65

Aluminum s trip, thickness range 0.045­

0.080 $2.12 $1.34 $1.67 $2.12 $1.46 $1.60 $1.60 $1.57

Kraft i nsulating paper with diamond

adhesive $1.66 $1.42 $1.65 $1.66 $1.63 $1.66 $1.66 $1.67

Mineral o il $1.82 $1.56 $1.83 $1.82 $1.74 $1.91 $1.85 $1.84

Tank s teel $0.50 $0.38 $0.44 $0.50 $0.46 $0.42 $0.39 $0.41

The Department then marked up the raw material prices presented in Table 5.4.1 using the

manufacturer’s internal markups discussed in section 5.4. For example, a raw material price of

$1.00/lb. would be marked up to $1.44/lb., reflecting the handling and scrap factor (2.5 percent), the

factory overhead (12.5 percent), and the non­production markup (25 percent). The Department then

used the marked­up material prices as inputs to the transformer design software. During the

manufacturer site visits in early 2002, the Department found this approach to be consistent with that

of several manufacturers who operate their own, proprietary transformer design software. Table

5.4.2 shows t he markup steps being applied to the five­year average material price scenario

(2002–2006).

5­31Table 5.4.2 Marked­up Material Prices for Liquid­Immersed Units, Five­Year Average Price

Scenario

Item and Description Material

P rice* Scrap &

Handling Factory

O verhead NonP roduction Software

I nput

M2 c ore steel $1.16 1.025 1.125 1.25 $1.67

M3 c ore steel $1.06 1.025 1.125 1.25 $1.53

M4 c ore steel $1.02 1.025 1.125 1.25 $1.47

M6 c ore steel $0.92 1.025 1.125 1.25 $1.32

ZDMH ( mechanically­scribed steel) $1.63 1.025 1.125 1.25 $2.34

SA1 ( amorphous) ­ finished core volume production $2.14 1.015 1.125 1.25 $3.06

Copper w ire, formvar round #10­20 (DL 1,2,4) $2.58 1.025 1.125 1.25 $3.73

Copper w ire, enameled round #7­10 flattened (DL 3,5) $2.62 1.025 1.125 1.25 $3.77

Copper w ire, enameled rectangular sizes (DL 3) $2.80 1.025 1.125 1.25 $4.04

Aluminum w ire, formvar round #9­17 (DL 1,2,4) $1.53 1.025 1.125 1.25 $2.20

Aluminum w ire, formvar round #7­10 (DL 3,5) $1.55 1.025 1.125 1.25 $2.23

Copper s trip, thickness range 0.02­0.045 (DL 1,2,4) $2.69 1.025 1.125 1.25 $3.88

Copper s trip, thickness range 0.030­0.060 (DL 3,5) $2.61 1.025 1.125 1.25 $3.76

Aluminum s trip, thickness range 0.02­0.045 (DL 1,2,4) $1.70 1.025 1.125 1.25 $2.45

Aluminum s trip, thickness range 0.045­0.080 (DL 3,5) $1.67 1.025 1.125 1.25 $2.41

Kraft in sulating paper with diamond adhesive $1.65 1.025 1.125 1.25 $2.38

Mineral o il (per gallon) $1.83

­ 1.125 1.25 $2.58

Tank S teel $0.44 1.025 1.125 1.25 $0.64

* Five y ear average (2002– 2006) for materials expressed in 2006$ per lb.

In the NOPR analysis, the Department had considered ZDMH core steel with a 31 percent

anti­dumping import duty, which had applied to all core steel produced in Japan. The duty only

applies to ZDMH raw material; it does not apply to the material if ‘substantial rework’ were done

prior to importation (e.g., building a transformer or a core outside the U.S. and then importing it).

Therefore, this material had been considered in the analysis as a finished core. However, for the

final rule, this import duty was no longer active, and therefore the ZDMH price point considered was

simply the raw material price. Core fabrication was assumed to take place at the manufacturer’s

plant, rather than being purchased by the manufacturer as a finished core.

For d iscussion on the review of amorphous material pricing, please see section 5.7 of this

Chapter.

5­32In addition to the aforementioned materials that vary during the design optimization process

(e.g., core steel, windings, insulation), there are other direct materials inputs that are fixed costs and

generally do not influence the design or vary with efficiency rating. These include direct materials,

such as the high­ and low­voltage bushings and the core clamps. The Department also prepared

estimates of the tank fabrication cost, based on the optimized transformer design (the software

considers this variable) and the labor necessary to build the tank. Table 5.4.3 summarizes all the

estimated fixed material costs and estimates of the tank costs for each of the five liquid­immersed

design lines.

For d esign line 1, a 50kVA single­phase pad­mounted unit, the high­voltage bushings are

two universal bushing wells, 15 kV, 95 BIL, 14400V, costing $7 each. The low­voltage bushings

are three threaded copper studs, 240/120V, 50 kVA, costing $20 for the set. Internal hardware costs

include a core clamp, nameplate, and other miscellaneous hardware costing $25.65. The finished

tank size (and associated cost) varies by design, but the average is approximately $130.

For d esign line 2, a 25kVA single­phase pole­mounted unit, the high­voltage terminal is a

single, wet­process porcelain bushing assembly, 15 kV, 125 BIL, costing $6.00. The low­voltage

terminals are three molded polymer bushings, 120/240V, 25 kVA, costing $8.00 for the set. Internal

hardware costs include a core clamp, nameplate, and other miscellaneous hardware, costing $19.15.

The finished tank sizes (height and diameter) vary by design, but the average is approximately $70.

For d esign line 3, a 500kVA single­phase unit, the high­voltage connector is a single, wetprocess porcelain bushing, 25 kV, 125 BIL, costing $6.00. The low­voltage bushings are two fourhole “J” Spade 500kVA, 277V, costing $60 for the set. The internal hardware includes a core clamp

($30), nameplate ($0.65), and miscellaneous hardware ($20), totaling $50.65. The design software

optimized the tank cost with each design, including radiators (external cooling) for this kVA rating.

The resultant finished round tank has a diameter of 33" to 52", with an average cost of

approximately $500 (including radiators).

For d esign line 4, a 150kVA three­phase, pad­mounted unit, the high­voltage bushings are

three externally clamped, universal high­voltage bushing wells, 8.3/14.4 kV, 95 BIL, costing $7

each. The low­voltage bushings are three copper studs at $8 each. The internal hardware includes

core clamps ($30), nameplate ($0.65), and miscellaneous hardware ($45), totaling $75.65 The

optimized finished tank sizes measure 50 inches high and vary in width and depth. The finished

rectangular, welded tank has an average cost of approximately $360.

For d esign line 5, a 1500kVA three­phase, pad­mounted unit, the high­voltage bushings are

three externally clamped, universal high­voltage bushing wells, 15.2/26.3 kV, 125kV BIL, costing

$20 each. The low­voltage bushings are four externally clamped bushings, each having six­hole

spade, costing $160 for the set. The internal hardware includes core clamps ($60), nameplate

($0.65), and miscellaneous hardware ($45), totaling $105.65. The optimized finished tank sizes

measure 70 inches high and vary in width and depth. The finished rectangular, welded tank,

including radiators as specified by the design software, has an average cost of approximately $800.

5­33Table 5.4.3 Summary Table of Fixed Material Costs for Liquid­Immersed Units

Item DL 1 DL 2 DL 3 DL 4 DL 5

High v oltage bushings $14 $6 $6 $21 $60

Low v oltage bushings $20 $8 $60 $24 $160

Core c lamp, nameplate, and misc. hardware $25.65 $19.15 $50.65 $75.65 $105.65

Transformer t ank average cost* ~$150 ~$80 ~$650 ~$450 ~$1,100

* Transformer ta nk steel is used in the design optimization software and varies with the efficiency (and size) of each

design. DL3 and DL5 include calculated costs of radiators, which are scaled for each design based on the required

cooling surface area.

5.4.3 Material I nputs to the Design Software—Dry­type

Table 5 .4.4 presents the material prices for a typical dry­type transformer manufacturer in Q1

2005, the hypothetical low material prices (for the LCC material price sensitivity, presented in

Chapter 8), and the 2002–2006 five­year average prices (all in constant 2006$). The highlighted

columns are the prices used in the engineering analysis.

5­34Table 5.4.4 Manufacturer’s Material Prices for Dry­Type Design Lines

Material 2006

$ /lb. 2002

­ 15%

2006$/

lb. 5­yr

A vg.

2006$/

lb. 2006

2 006$/

lb. 2005

2 006$/

lb. 2004

2 006$/

lb. 2003

2 006$/

lb. 2002

2 006$/

lb.

H­O D R core steel (domain­refined) $1.76 $0.89 $1.27 $1.76 $1.51 $1.06 $0.99 $1.05

M3 c ore steel $1.62 $0.73 $1.07 $1.62 $1.16 $0.85 $0.84 $0.86

M4 c ore steel $1.59 $0.69 $1.02 $1.59 $1.12 $0.80 $0.77 $0.81

M5 c ore steel $1.55 $0.64 $0.97 $1.55 $1.10 $0.77 $0.68 $0.76

M6 c ore steel $1.50 $0.62 $0.95 $1.50 $1.07 $0.73 $0.73 $0.72

M19 c ore steel (26 gauge) $0.73 $0.46 $0.61 $0.73 $0.63 $0.58 $0.56 $0.55

M36 c ore steel (29 gauge) $0.65 $0.45 $0.56 $0.65 $0.53 $0.56 $0.52 $0.52

M36 c ore steel (26 gauge) $0.60 $0.39 $0.51 $0.60 $0.48 $0.54 $0.47 $0.46

M43 c ore steel (26 gauge) $0.57 $0.39 $0.48 $0.57 $0.42 $0.51 $0.46 $0.46

Rectangular c opper wire 0.1 x 0.2, Nomex $5.20 $1.50 $2.87 $5.20 $2.09 $2.89 $2.41 $1.76

Rectangular a luminum wire 0.1 x 0.2, Nomex $1.91 $1.84 $2.06 $1.91 $1.93 $2.16 $2.16 $2.16

Copper s trip, thickness range 0.020­0.045 $4.74 $1.93 $2.99 $4.74 $2.87 $2.65 $2.41 $2.27

Aluminum s trip, thickness range 0.020­0.045 $2.01 $1.40 $1.70 $2.01 $1.45 $1.70 $1.70 $1.65

Nomex in sulation (per pound) $17.07 $16.57 $18.14 $17.07 $15.96 $19.10 $19.09 $19.50

Cequin in sulation (per pound) $8.50 $11.37 $11.07 $8.50 $7.67 $12.73 $13.09 $13.37

Impregnation ( per gallon) $21.35 $16.10 $18.57 $21.35 $14.93 $19.10 $18.55 $18.94

Winding c ombs (per pound) $7.56 $9.47 $9.47 $7.56 $7.15 $10.61 $10.91 $11.14

Enclosure S teel (per pound) $0.50 $0.38 $0.44 $0.50 $0.46 $0.42 $0.39 $0.41

On the following pages, all the material prices entered into the design software for dry­type

distribution transformers are given. As shown in these tables, the Department marked up the

material prices before being entering them into the design software.

5­35Table 5.4.5 Marked­up Material Prices for Dry­Type Units, Five­Year Average Price Scenario

Item and Description Material

P rice* Scrap &

Handling Factory

O verhead NonP roduction Software

I nput

H­O D R core steel (domain­refined) $1.27 1.025 1.125 1.25 $1.84

M3 c ore steel $1.07 1.025 1.125 1.25 $1.54

M4 c ore steel $1.02 1.025 1.125 1.25 $1.47

M5 c ore steel $0.97 1.025 1.125 1.25 $1.40

M6 c ore steel $0.95 1.025 1.125 1.25 $1.37

M19 c ore steel (26 gauge) $0.61 1.025 1.125 1.25 $0.88

M36 c ore steel (29 gauge) $0.56 1.025 1.125 1.25 $0.80

M36 c ore steel (26 gauge) $0.51 1.025 1.125 1.25 $0.74

M43 c ore steel (26 gauge) $0.48 1.025 1.125 1.25 $0.70

Rectangular c opper wire, 0.1 x 0.2, Nomex $2.87 1.025 1.125 1.25 $4.14

Rectangular a luminum wire, 0.1 x 0.2, Nomex $2.06 1.025 1.125 1.25 $2.98

Copper s trip, thickness range .02­.045 $2.99 1.025 1.125 1.25 $4.31

Aluminum s trip, thickness range .02­.045 $1.70 1.025 1.125 1.25 $2.45

Nomex in sulation (per pound) $18.14 1.025 1.125 1.25 $26.15

Cequin in sulation (per pound) $11.07 1.025 1.125 1.25 $15.96

Impregnation ( per gallon) $18.57

­ 1.125 1.25 $26.12

Enclosure s teel (per pound) $9.47 1.025 1.125 1.25 $13.66

Winding C ombs (per pound) $0.44 1.025 1.125 1.25 $0.64

* Five y ear average (2002– 2006) for materials expressed in 2006$ per lb.

As stated in section 5.3, the OPS software does not take into account retooling costs

associated with changing production designs. Therefore, to partially capture these differential costs

in the design line that had both buttlap and mitered designs, the Department used an adder in design

line 9. The adder specified an extra 10 cents per pound of core steel for full­mitered designs. More

detailed costing of the retooling costs for mitering equipment is captured in the MIA (see Chapter

12).

Similar t o the liquid­immersed designs, there are fixed (and some partially variable)

hardware costs associated with dry­type distribution transformers. These are discussed individually

and then summarized in Table 5.4.6.

For d esign line 9, a 300 kVA three­phase, medium­voltage dry­type transformer at 45 kV

BIL, the low­voltage and high­voltage terminal set costs $75. The secondary (low­voltage) bus­bar

is estimated to be eight feet at $10 per foot, or $80. The mounting frame that attaches the core/coil

assembly to the transformer enclosure costs approximately $36. The fiberglass dog­bone ductspacers used for this design line cost $0.42 per foot. The Department estimated the miscellaneous

hardware costs at $25. The ventilated enclosure ­ a 14­gauge steel enclosure, base, and mounting

feet ­ varies with the size of the core­coil assembly for the 300 kVA unit, and costs approximately

$175.

For d esign line 10, a 1500 kVA three­phase, medium­voltage dry­type transformer at 45 kV

BIL, the low­voltage and high­voltage terminal set costs $120. The low­voltage bus­bar is estimated

to be fourteen feet at $10 per foot, or $140. The mounting frame that attaches the core/coil assembly

5­36to the transformer enclosure costs approximately $120. The fiberglass dog­bone duct­spacers used

for this design line cost $0.52 per foot. The Department estimated the miscellaneous hardware costs

at $42. The ventilated enclosure ­ a 12­gauge steel enclosure, base, and mounting feet ­ varies with

the size of the core­coil assembly for the 1500 kVA unit, and costs approximately $600.

For d esign line 11, a 300 kVA three­phase, medium­voltage dry­type at 95 kV BIL, the lowvoltage and high­voltage terminal set costs $100. The high­voltage terminal boards cost $27. The

low­voltage bus­bar is estimated to be ten feet at $8 per foot, or $80. The mounting frame that

attaches the core/coil assembly to the transformer enclosure costs $42. The fiberglass dog­bone

duct­spacers used for this design line cost $0.42 per foot. The Department estimated the

miscellaneous hardware costs at $32. The ventilated enclosure ­ a 14­gauge steel enclosure, base,

and mounting feet ­ varies with the size of the core­coil assembly for the 300 kVA unit, and costs

approximately $300.

For d esign line 12, a 1500 kVA three­phase, medium­voltage dry­type at 95 kV BIL, the

low­voltage and high­voltage terminal set costs $135. The high­voltage terminal boards cost $27.

The low­voltage bus­bar is estimated to be sixteen feet at $12 per foot, or $192. The mounting

frame that attaches the core/coil assembly to the transformer enclosure costs $125. The fiberglass

dog­bone duct­spacers used for this design line cost $0.56 per foot. The Department estimated the

miscellaneous hardware costs at $54. The ventilated enclosure ­ a 12­gauge steel enclosure, base,

and mounting feet ­ varies with the size of the core­coil assembly for the 1500 kVA unit, and costs

approximately $770.

For d esign line 13, a 2000 kVA three­phase, medium­voltage dry­type at 125 kV BIL, the

low­voltage and high­voltage terminal set costs $150. The high­voltage terminal boards cost $27.

The low­voltage bus­bar is estimated to be eighteen feet at $15 per foot, or $270. The mounting

frame that attaches the core/coil assembly to the transformer enclosure costs $175. The fiberglass

dog­bone duct­spacers used for this design line cost $0.60 per foot. The Department estimated the

miscellaneous hardware costs at $60. The ventilated enclosure ­ a 12­gauge steel enclosure, base,

and mounting feet ­ varies with the size of the core­coil assembly for the 2000 kVA unit, and costs

approximately $835.

Table 5 .4.6 Summary Table of Fixed Material Costs for Dry­Type Units

Item DL 9 DL 1 0 DL 1 1 DL 1 2 DL 1 3

LV a nd HV terminals (set) $75 $120 $100 $135 $150

HV t erminal board(s) $27 $27 $27 $27 $27

LV b us­bar $80 $140 $80 $192 $270

Core/coil m ounting frame $36 $120 $42 $125 $175

Nameplate $0.65 $0.65 $0.65 $0.65 $0.65

Dog­bone d uct­spacer (ft.) $0.42 $0.52 $0.42 $0.56 $0.60

Winding c ombs (lb.) n/a n/a $10.24 $10.24 $10.24

Misc. h ardware $25 $42 $32 $54 $60

Enclosure ( 12, 14 gauge) ~$300 ~$850 ~$450 ~$900 ~$1050

5­37LV

= low voltage

HV

= high voltage

5.4.4 Labor C osts

Labor c osts are a critical aspect of the cost of manufacturing a distribution transformer. The

Department used the same hourly labor cost for both liquid and dry­type distribution transformers. It

developed the hourly cost of labor using a similar approach to the development of the cost of

materials; however, it used different markups, with the exception of the non­production markup.

The Department developed the markups shown in Table 5.4.7 after reviewing publicly available

information and consulting with industry experts familiar with transformer manufacturing in the

U.S.

Table 5 .4.7 Labor Markups for Liquid­Immersed and Dry­Type Manufacturers

Item description Markup percentage Rate p er hour

Labor c ost per hour * $ 14.31

Indirect P roduction ** 33% $ 1 9.03

Overhead *** 30% $ 2 4.74

Fringe † 21% $ 2 9.93

Assembly L abor Up­time †† 43% $ 4 2.77

Non­Production M ark­up ††† 25% $ 5 3.46

Cost o f Labor Input to Software $ 5 3.46

* Cost p er hour is from U.S. Census Bureau, 1997 Economic Census of Industry

, published September 1999, Table 5,

page 9. Data for NAICS code 3353111 "Power and distribution transformers, except parts" Production workers hours

and wages.

** Indirect p roduction labor (e.g., production managers, quality control) as a percent of direct labor on a cost basis.

Navigant Consulting, Inc. (NCI) estimate.

*** Overhead in cludes commissions, dismissal pay, bonuses, vacation, sick leave, and social security contributions.

NCI estimate.

† Fringe includes pension contributions, group insurance premiums, workers compensation. Source: U.S. Census

Bureau, 1997 Economic Census of Industry

, published September 1999, Table 3, page 8. Data for NAICS code 335311

"Power, Distribution and Specialty Transformer Manufacturing," Total fringe benefits as a percent of total compensation

for all employees (not just production workers).

†† Assembly labor up­time is a factor applied to account for the time that workers are not assembling product and/or

reworking unsatisfactory units. The markup of 42 percent represents a 70 percent utilization (multiplying by 100/70).

NCI estimate.

††† Non­production markup reflects non­production costs, including selling, general, and administrative, R&D, interest

payments, and profit factor markups. Source: US Industry Census Data for 1992 and 1997; SEC 10­K reports for Acme,

Powell, Magnetek and Hammond; Manufacturer interviews, 2002.

There are several labor steps involved in manufacturing a liquid­immersed transformer. The

Department prepared estimates of the amount of labor involved, some varying with the transformer

design and others fixed on a per­unit basis. These steps are described below, and the amount of time

dedicated to each is given in Table 5.4.8.

• Cutting, F orming, and Annealing ­ This task involves cutting the core steel to lengths on a

distributed­gap core cutting machine, forming the resulting “donut” of core steel into a

5­38rectangular shape in a hydraulic press, and then annealing the core in a high temperature

annealing furnace. The labor involved in these activities is calculated based on the weight of

core (pounds) multiplied by a constant, which varies with the lamination thickness of the

core steel. For DL1, DL2, and DL4, on M6 designs the constant is 0.08, M4 is 0.10, M3 and

ZDMH are 0.125, and M2 is 0.16. For DL3 and DL5, on M6 designs the constant is 0.05,

M4 is 0.07, M3 and ZDMH are 0.09, and M2 is 0.11. For the prefabricated core

— SA1

(Amorphous material)—the labor for cutting, forming, and annealing is set to zero.

• Primary W inding ­ This task entails winding the primary conductor of the transformer. It

includes set­up time as well as winding time. The labor hours vary with the number of turns

(per phase) for the primary winding. For DL1, DL2, and DL4 the winding time is 0.0001

hours per turn. For these smaller kVA ratings (and smaller cores), this rate is very low

because some of the larger, liquid­immersed manufacturers wind multiple coils

simultaneously on the same winding machine. This manufacturing approach improves

throughput and productivity at the facility. The rate of 0.0001 hours per turn equates to

approximately one­third of a second per turn. On DL3 and DL5, due to the larger coil size

associated with these units, the winding time is 0.002 hours per turn (approximately 7.2

seconds per turn).

• Secondary W inding ­ This task involves winding the secondary conductor of the transformer.

It includes set­up time as well as winding time. On a distribution (step­down) transformer,

the number of secondary turns is always less than the primary. For the liquid­immersed

units, which are taking a relatively high primary voltage and dropping to below 600V, the

turns ratio can be as large as 100:1. For this reason, the hours per turn of the secondary are

considerably higher than the primary, because there are fewer turns over which to amortize

the set­up time as well as a slower winding rate for the secondary, which has larger crosssectional area than the primary. For DL1, DL2, and DL4, the hours per turn of the secondary

are 0.015 (54 seconds per turn); for DL3 and DL5, the hours per turn are 0.02 (72 seconds

per turn).

• Lead D ressing ­ Once a wound coil is taken off the winding machine, work must be

performed on the leads to prepare them for the next manufacturing step. Enamel is removed

to enable good electrical connection and an insulating tubing is slipped over the cable. This

is a fixed amount of labor, and does not vary with efficiency or design. The estimated times

are 0.5 hours for DL1 and DL4, 0.07 hours for DL2, 0.35 hours for DL3, and 1.0 hour for

DL5.

• Coil V arnishing and Baking ­ Once they are complete, the coils are vacuum­dipped in

varnish and baked in an oven to cure the varnish and enhance the integrity of the coil. This

task varies slightly with kVA rating, but does not vary with efficiency. The estimated times

are 0.10 hours for DL1, 0.07 hours for DL2, 0.15 hours for DL3, 0.17 hours for DL4, and

0.25 hours f or DL5.

• Core A ssembly (“Lacing”) ­ This task involves assembling and banding the annealed wound

core laminations around varnished windings. The annealed bundle of core steel is

disassembled from the inside out by grabbing approximately 1/4 inch bundles, then

reassembling the core steel around the coils. Once all the laminations are reassembled, the

core material is clamped to maintain the structure. The activity involves feeding a banding

5­39strip around the core material and using a locking clamp to compress and contain the core

material. The labor rate varies with stack height and lamination thickness for each design.

The time for core assembly is approximately 0.5 hours for DL1, 0.3 hours for DL2, 1.5 hours

for DL3, 1 hour for DL4, and 3.5 hours for DL5.

• Tanking a nd Impregnating ­ This task involves inserting and fastening the core/coil assembly

into the tank. Then, a vacuum is pulled and oil is introduced to the tank. On round tanks,

the vacuum and oil step is done through a lid attached to the top of the unit. On the

rectangular and pad­mounted tanks, the vacuum is pulled in a chamber, which takes a little

longer per unit. Finally, tap changers and bushings are mounted, and bolted connections

made. The time for this activity does not vary with design or efficiency, but it does vary by

kVA rating and tank shape. The estimates of labor time for the five liquid­immersed design

lines are: 0.5 hours for DL1, 0.11 hours for DL2, 0.3 hours for DL3, 0.62 hours for DL4, and

1.4 hours f or DL5.

• Inspection

­ This activity involves verifying that the transformer is assembled properly and is

up to a manufacturer's quality specification. This task includes inspecting the lead dressing,

lead tie­up, and other quality certification specifications. The time for this activity does not

vary with design or efficiency, but it does vary by kVA rating. The estimates of labor time

are 0.10 hours for DL1 and DL3, 0.05 hours for DL2, 0.15 hours for DL4, and 0.20 hours for

DL5.

• Preliminary T est ­ This step involves conducting a test to ensure that the core/coil meets the

specified turns ratio, polarity, core loss, etc. The time for this activity does not vary with

design or efficiency, but it does vary by kVA rating. The estimates of labor time are 0.10

hours for DL1, DL3, and DL4; 0.03 hours for DL2; and 0.15 hours for DL5.

• Final T est ­ This activity involves testing of the final, assembled unit, with the core/coil

assembly immersed in oil. This test verifies that the unit meets the guaranteed values,

including core and coil losses, impedance, and dielectric tests. The time for this activity does

not vary with design or efficiency, but it does vary by kVA rating. The estimates of labor

time are 0.15 hours for DL1 and DL3, 0.07 hours for DL2, 0.20 hours for DL4, and 0.25

hours for DL5.

• Marking a nd Miscellaneous ­ This task involves preparing any extra markings around the

bushings or on the surface of the transformer and other miscellaneous labor associated with

preparing the finished transformer for the customer. The time for this activity does not vary

with design or efficiency, but it does vary by kVA rating. The estimates of labor time are

0.28 hours f or DL1, 0.07 hours for DL2, 0.35 hours for DL3, 0.31 hours for DL4, and 0.75

hours for DL5.

• Pallet L oading ­ This activity involves preparing the transformer for shipping to the

customer. This includes loading the finished transformer onto a pallet, banding the

transformer to the pallet, wrapping, and all other necessary steps for shipping. The time for

this activity does not vary with design or efficiency, but it does vary by kVA rating. The

estimates of labor time are 0.27 hours for DL1, 0.06 hours for DL2, 0.5 hours for DL3 and

DL4, and 3 hours for DL5.

5­40Table 5.4.8 summarizes the estimates of labor time that DOE used for the five liquidimmersed units.

Table 5 .4.8 Summary of Labor Times for Liquid­Immersed Units

Labor Activity DL 1

hrs. DL 2

hrs. DL 3

hrs. DL 4

hrs. DL 5

hrs.

Cutting, F orming, & Annealing ~1.00 ~0.75 ~4.00 ~3.00 ~8.50

Primary W inding (hrs/turn) 0.0001 0.0001 0.002 0.0001 0.002

Secondary W inding (hrs/turn) 0.015 0.015 0.020 0.015 0.020

Lead D ressing 0.50 0.07 0.35 0.50 1.00

Baking C oils 0.10 0.07 0.15 0.17 0.25

Core A ssembly ~0.50 ~0.30 ~1.50 ~1.00 ~3.50

Tanking a nd Impregnating 0.50 0.11 0.30 0.62 1.40

Inspection 0.10 0.05 0.10 0.15 0.20

Preliminary T est 0.10 0.03 0.10 0.10 0.15

Final T est 0.15 0.07 0.15 0.20 0.25

Pallet L oading 0.27 0.06 0.50 0.50 3.00

Marking a nd Misc. 0.28 0.07 0.35 0.31 0.75

Likewise, there are several labor steps involved in manufacturing a dry­type transformer.

The Department prepared estimates of the amount of labor involved, some varying with the

transformer design and others fixed on a per­unit basis. These steps are described below, and the

amounts of time dedicated to each are summarized in Table 5.4.9.

• Core S tacking ­ This task involves stacking (assembling) the cut steel laminations into a

distribution transformer core. The amount of labor for this task varies by kVA rating, stack

height, and whether the core is grain­oriented or non­oriented. Thus, the labor for core

stacking varies with the efficiency of the transformer. Approximate labor hours for core

stacking vary from as short as 0.45 hours/inch for a 300 kVA, 45kV BIL three­phase,

medium­voltage unit to 0.9 hours/ inch for a 2000 kVA, 125kV BIL three­phase, mediumvoltage unit.

• Primary W inding ­ This task encompasses winding the primary conductor of the transformer.

It includes set­up time as well as winding time. The labor hours vary with the number of

turns (per phase) for the primary winding. The 300kVA units, DL9 and DL11, both have

0.01 hours/turn. T he 1500kVA units, DL10, DL12, and the 2000kVA DL13 all have the

same winding time—0.0125 hours/turn.

• Secondary W inding ­ This task involves winding the secondary conductor of the transformer.

It includes set­up time as well as winding time. The hours per turn of the secondary are

considerably higher than the primary, because there are fewer turns over which to amortize

the set­up time as well as a slower winding rate for the secondary, which has larger

5­41cross­sectional area. The hours per turn vary from 0.035 to 0.125, depending on the kVA

rating (design line).

• Lead D ressing ­ Once a wound coil is taken off the winding machine, work must be

performed on the leads to prepare them for the next manufacturing step. Enamel is removed

to enable good electrical connection and an insulating tubing is slipped over the cable. For a

given kVA rating, this is a fixed amount of labor, and does not vary with efficiency or

design. The range is from 0.60 to 1.0 hours per unit.

• Assembly

­ This task involves installing the wound cores onto the partially assembled core,

and then lacing the top (yoke) laminations to complete the core. It also includes setting all

the core clamps and completing the core/coil assembly. The Department assumed the

assembly time varies by kVA rating, but does not vary by design within a kVA rating. For

example, the assembly time for a 1500kVA three­phase unit is estimated at six hours, while

the assembly time for a 300kVA three­phase unit is estimated at three hours.

• Inspection

­ This activity involves verifying that the transformer is assembled properly and is

up to a manufacturer's quality specification. It includes inspecting the lead dressing, lead

tie­up, and other quality certification specifications. The time for this activity does not vary

with design or efficiency, but it does vary by kVA rating. The time estimates vary from 0.10

hours (6 minutes) for the smaller kVA ratings to 0.25 hours (15 minutes) for the larger units.

• Preliminary T est ­ This step involves conducting a test to ensure that the core/coil meets the

specified turns ratio, polarity, core loss, etc. The time for this activity does not vary with

design or efficiency, but it does vary by kVA rating. The estimates of labor time range from

0.10 hours ( 6 minutes) for the smaller kVA ratings to 0.5 hours (30 minutes) for the larger

units.

• Final T est ­ This activity involves testing the final, assembled unit, with the core/coil

assembly immersed in oil. This test verifies that the unit meets the guaranteed values,

including core and coil losses, impedance, and dielectric tests. The time for this activity does

not vary with design or efficiency, but it does vary by kVA rating. Similar to the preliminary

test, the labor time estimates range from 0.15 hours (9 minutes) for the smaller kVA ratings

0.75 hours ( 45 minutes) for the larger units.

• Marking a nd Miscellaneous ­ This task involves preparing any extra markings on the

terminal board or on the surface of the transformer, and other miscellaneous labor associated

with preparing the finished transformer for the customer. The time for this activity does not

vary with design or efficiency, but it does vary by kVA rating. The labor estimate ranges

from 0.70 hours at the low end to 2.2 hours at the higher kVA ratings.

• Packing

­ This activity involves preparing the transformer for shipping to the customer. This

includes loading the finished transformer onto a pallet, banding the transformer to the pallet,

wrapping, and all other necessary steps for shipping. The time for this activity does not vary

with design or efficiency, but it does vary by kVA rating. The time estimate ranges from 1.0

hours at the low end to 2.0 hours at the higher kVA ratings.

5­42• Enclosure M anufacturing ­ The labor estimate for this task encompasses all activity

associated with the cutting, forming, assembly, priming, painting, and preparation of the

enclosure. This labor estimate varies with the kVA rating, spanning from five hours for the

300kVA up to eight hours for the 1500 and 2000kVA cabinets.

Table 5 .4.9 presents the hours of labor needed to complete each step in the manufacturing

process for all design lines containing dry­type transformers.

Table 5 .4.9 Summary of Labor Times for Dry­Type Units

Labor Activity DL 9

hrs. DL 1 0

hrs. DL 1 1

hrs. DL 1 2

hrs. DL 1 3

hrs.

Core S tacking (hrs/inch) 0.45­0.55 0.70 0.70 0.80 0.90

Primary W inding (hrs/turn) 0.01 0.0125 0.01 0.0125 0.0125

Secondary W inding (hrs/turn) 0.035 0.125 0.035 0.125 0.125

Lead D ressing 0.60 1.00 0.60 1.00 1.00

Assembly 3.00 6.00 4.00 6.00 6.00

Inspection 0.10 0.25 0.10 0.25 0.25

Preliminary T est 0.10 0.50 0.15 0.50 0.50

Final T est 0.15 0.75 0.25 0.75 0.75

Enclosure M anufacturing 5.00 8.00 5.00 8.00 8.00

Packing 1.00 2.00 1.00 2.00 2.00

Marking a nd Miscellaneous 0.70 2.20 0.80 2.20 2.20

5­435.5 RESULTS O F THE ANALYSIS ON EACH DESIGN LINE

This s ection provides a visual representation of the results of the engineering analysis. The

scatter plots in this section show the relationship between the manufacturer’s selling price and

efficiency for each of the 10 design lines. Each dot on the plots represents one unique design created

by the software at a given manufacturer’s selling price and efficiency level. The placement of each

dot (and the uniqueness of each design) is dictated by the design option combinations (core steel and

windings), core shape, A/B combination, and the variable design parameters generated by the design

software. In addition to the results provided in this section, the Department prepared scatter plots

depicting the engineering analysis results for the 10 representative units, including watts of core and

coil loss and the weight by efficiency (see Appendix 5A).

As d iscussed earlier in this chapter, the Department received several comments on the NOPR

analysis that material prices, and particularly core steel, were experiencing a rapid increase.

Therefore, in addition to its analysis on a five­year average material price (2002–2006) presented

here, the Department also conducted a current price scenario using 2006 prices. The engineering

analysis results of the 2006 material price sensitivity scenario are presented in Appendix 5C, along

with a comparison between these material prices and the five­year average. The Department also

calculated a hypothetical low­materials­price scenario, which represents a 15 percent reduction over

the materials prices in 2002 (the year in which M6 had the lowest $/pound between 2002 and 2006).

The results of the low­price scenario are included in the LCC spreadsheets, where they were used for

an LCC sensitivity analysis.

5­44Figure 5.5.1 presents a plot of the manufacturer selling prices and efficiency levels for the

full database of designs for the representative unit from design line 1, a 50kVA single­phase, liquidimmersed, pad­mounted distribution transformer. The efficiency levels shown in this plot represent

transformers at 50 percent of nameplate load and are corrected for temperature.

Figure 5.5.1 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 1

5­455­46 Figure 5.5.2 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 2, a 25kVA single­phase, liquidimmersed, pole­mounted distribution transformer.  The efficiency levels shown in this plot represent

transformers at 50 percent of nameplate load and are corrected for temperature.

$500 $750 $1,000 $1,250 $1,500 $1,750 $2,000

97.80% 98.00% 98.20% 98.40% 98.60% 98.80% 99.00% 99.20% 99.40% 99.60%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_sh

M6CuAl_sh

M4AlAl_sh

M4CuAl_sh

M3CuAl_sh

M3CuCu_sh

M2CuAl_sh

M2CuCu_sh

ZDMHCuCu_sh

SACuCu_co

TSLs TSL

B,C

TSL4,D TSL1

TSL3 TSL2 TSL

6 TSL A

TSL 5

Figure 5.5.2 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 2Figure 5.5.3 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 3, a 500kVA single­phase, liquidimmersed distribution transformer with radiators. The efficiency levels shown in this plot represent

transformers at 50 percent of nameplate load and are corrected for temperature.

Figure 5.5.3 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 3

5­475­48 Figure 5.5.4 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 4, a 150kVA three­phase, liquidimmersed distribution transformer.  The efficiency levels shown in this plot represent transformers at

50 percent of nameplate load and are corrected for temperature.

$2,000 $3,000 $4,000 $5,000 $6,000 $7,000 $8,000

98.20% 98.40% 98.60% 98.80% 99.00% 99.20% 99.40% 99.60% 99.80%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_co

M4AlAl_co

M3CuAl_co

M2CuAl_co

M2CuCu_co

ZDMHCuCu_co

SA1CuCu_co

TSLs TSL1 TSLA TSL5 TSL2,B,

C,D TSL3,4 TSL6

Figure 5.5.4 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 4Figure 5.5.5 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 5, a 1500kVA three­phase, liquidimmersed distribution transformer. The efficiency levels shown in this plot represent transformers at

50 percent of nameplate load and are corrected for temperature.

Figure 5.5.5 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 5

5­495­50 Figure 5.5.6 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 9, a 300kVA three­phase, mediumvoltage, dry­type transformer with a 45kV BIL.  The efficiency levels shown in this plot represent

transformers at 50 percent of nameplate load and are corrected for temperature.

$4,000 $6,000 $8,000 $10,000 $12,000 $14,000

98.40% 98.60% 98.80% 99.00% 99.20% 99.40%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_bl

M6CuCu_mt

M5AlAl_mt

M3CuAl_mt

HOCuCu_mt

TSLs TSL1 TSL2 TSL3 TSL4 TSL5,6

Figure 5.5.6 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 95­51 Figure 5.5.7 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 10, a 1500kVA three­phase,

medium­voltage, dry­type transformer with a 45kV BIL.  The efficiency levels shown in this plot

represent transformers at 50 percent of nameplate load and are corrected for temperature.

$16,000 $21,000 $26,000 $31,000 $36,000 $41,000 $46,000

98.70% 98.80% 98.90% 99.00% 99.10% 99.20% 99.30% 99.40% 99.50% 99.60%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_cf

M6CuCu_cf

M4CuAl_cf

M3CuCu_cf

HOCuCu_cf

TSLs TSL1 TSL2 TSL3 TSL4 TSL5,6

Figure 5.5.7 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 105­52 Figure 5.5.8 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 11, a 300kVA three­phase, mediumvoltage, dry­type transformer with a 95kV BIL.  The efficiency levels shown in this plot represent

transformers at 50 percent of nameplate load.

$7,000 $8,000 $9,000 $10,000 $11,000 $12,000 $13,000 $14,000 $15,000

97.80% 98.00% 98.20% 98.40% 98.60% 98.80% 99.00% 99.20%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_mt

M6CuCu_mt

M4CuAl_mt

M3CuCu_mt

HOCuCu_mt

TSLs TSL1 TSL2 TSL3 TSL4 TSL5,

6

Figure 5.5.8 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 115­53 Figure 5.5.9 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 12, a 1500kVA three­phase,

medium­voltage, dry­type transformer with a 95kV BIL.  The efficiency levels shown in this plot

represent transformers at 50 percent of nameplate load.

$15,000 $20,000 $25,000 $30,000 $35,000 $40,000 $45,000 $50,000 $55,000

98.70% 98.80% 98.90% 99.00% 99.10% 99.20% 99.30% 99.40% 99.50% 99.60%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_cf

M6CuCu_cf

M4CuAl_cf

M3CuCu_cf

HOCuCu_cf

TSL levels TSL1 TSL2 TSL3 TSL4 TSL5,6

Figure 5.5.9 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 125­54 Figure 5.5.10 presents a plot of the manufacturer sales prices and efficiency levels for the full

database of designs for the representative unit from design line 13, a 2000kVA three­phase,

medium­voltage, dry­type transformer with a 125kV BIL.  The efficiency levels shown in this plot

represent transformers at 50 percent of nameplate load and are corrected for temperature.

$20,000 $25,000 $30,000 $35,000 $40,000 $45,000 $50,000 $55,000 $60,000 $65,000 $70,000

98.90% 99.00% 99.10% 99.20% 99.30% 99.40% 99.50% 99.60%

Efficiency at 50% load, Temperature CorrectedManufacturer Selling Price ($) M6AlAl_cf

M6CuCu_cf

M4CuAl_cf

M3CuCu_cf

HOCuCu_cf

TSLs

TSL1 TSL2 TSL3 TSL4 TSL5,6

Figure 5.5.10 Engineering Analysis Results, 2002­2006 Average Material Prices, Design Line 135.6 TEAR­DOWN ANALYSIS

As d iscussed in the NOPR TSD, the Department purchased, tested, disassembled, and

analyzed six transformers from design line 7 for the engineering analysis. Although this technical

support document (TSD) does not contain analysis results for design line 7 due to passage of the

Energy Policy Act of 2005, this tear­down analysis is important for two reasons: 1) to demonstrate

the predictive accuracy of the OPS software, and 2) to validate the transformer designs. The

Department selected design line 7 because this design line has the largest energy savings potential

and because the representative unit (75 kVA three­phase, low­voltage, dry­type) is readily available

from wholesale distributors. This section discusses the tear­down analysis on the six transformers

and the results.

The D epartment purchased six transformers in early 2004—two ‘matched pairs’ from three

manufacturers. The two transformers from each manufacturer represented a low­first­cost unit and a

NEMA TP­1/Energy Star unit. The transformers were shipped directly to the testing facility,

Transformer Engineering Corporation (TEC) in Cleveland, Ohio. TEC has been a manufacturer of

custom­designed transformers, inductors, and other electro­magnetic components since 1937. TEC

has a 50,000­square­foot facility in Cleveland, which includes a top­notch testing laboratory.

The D epartment reviewed several manufacturer catalogues and identified matched pairs of

low­first­cost and NEMA TP­1 units. It purchased these units from a local distributor, and shipped

them to TEC for testing. In Cleveland, the transformers were subjected to the following tests:

o C ore loss test

o C onductor resistance test

o C onductor loss test

o T emperature test

The D epartment recorded data for each of these tests, documenting all the critical

performance metrics for each of the six designs. It then carefully disassembled the transformers,

paying attention to the construction techniques, including type of steel and conductor. The

Department weighed all the pieces, and recorded physical attributes, such as core dimensions and

number of turns. It then put all of these physical dimensions into the OPS software, to model the

transformer that had just been disassembled. The OPS software used its electrical analysis program

to predict the values that had been measured in the laboratory. This step validated the predictive

capability of the software for generating performance metrics associated with its modeled designs.

The OPS software accurately predicted the efficiency (including the core and coil losses), the

impedance, the inductance, and all the transformer performance metrics.

Once t he NOPR engineering analysis designs were completed, the Department used the

results of the tear­down analysis to create a manufacturer’s selling price. In other words, using

measured variables such as the pounds of core steel and pounds of conductor, the Department costed

out the torn­down units using the same average material prices and mark­ups, as it had done for the

engineering analysis. The Department then plotted these six dots on the NOPR manufacturer’s

selling price­efficiency curve generated for design line 7. Figure 5.7.1 presents the plot of these

torn­down units. The six transformer tear­downs align perfectly with the design line 7 costefficiency curve.

5­555­56 5.7 REVIEW OF AMORPHOUS MATERIAL PRICING

As discussed in this chapter, DOE obtained updated material prices for the Final Rule

engineering analysis.  Included in that update was a revised price for a finished (prefabricated)

amorphous material transformer core.  This price was based on amorphous ribbon manufactured in

the US, being shipped to India for processing into cores, and then being shipped back to a US­based

transformer manufacturer. On a dollar per pound basis for the final rule, DOE found that the five

year average price of finished amorphous cores were $2.14 per pound (the five­year average spanned

2002­2006).  DOE’s high price scenario utilized the 2006 average annual price of $2.20 per pound.

In the NOPR, DOE had used a five year average of $2.00 per pound (the average spanning from

2000­2004) with a Q1 2005 sensitivity price of $2.50 per pound.  As discussed in the Final Rule

Federal Register Notice (see section V.A.1.c), DOE received comment from stakeholders requesting

that DOE review this pricing, as at least one stakeholder (the manufacturer of amorphous ribbon)

who asserted that the price per pound was too high.  This section provides detail on the review that

DOE conducted.

DOE’s finished amorphous core price was based on amorphous ribbon manufactured in the

US (Conway, South Carolina), being shipped to India for processing into cores, and then being

shipped back to a US­based transformer manufacturer.  DOE contracted Matrix Power, Inc. which 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

94.50% 95.00% 95.50% 96.00% 96.50% 97.00% 97.50% 98.00% 98.50% 99.00% 99.50%

Efficiency at 35% loadManfacturer Selling Price ($) M36AlAl_bl

M19AlAl_bl

M6AlAl_bl

M6AlAl_mtt

M6AlAl_mtf

M4CuAl_mtf

M3CuCu_mtf

HOCuCu_mtf

Teardowns TP­1: 98.0%

Manufacturer A:

Low Eff  M36_bl Manufacturer B:

Low Eff  M19_bl

Manufacturer C:

Low Eff  M36_bl Manufacturer B:

High Eff  M6_bl Manufacturer C:

High Eff  M5_mt Manufacturer A:

High Eff  M6_mt

Figure 5.6.1 Tear­down Plot Comparison, Design Line 7, 75kVA Three­phase Dry­typehas first­hand experience handling the export of amorphous ribbon and import of finished cores to

assist in the review of the shipment and processing costs. The costing of the finished cores was

based on a shipment estimate for a forty foot container loaded with 40,000 pounds of amorphous

metal ribbon from Conway, South Carolina to Gurgaon (Haryana), India.

Table 5 .7.1 Forty­foot Container from Conway, SC to Guragaon, India

Item Cost ( US$)

Freight C harges Door to Door (South Carolina to India) $4,500

Handling $95

AES a Filing Fee:(for filing Shipper's Export Declaration) $20

Courier $55

Customs C learance $200

D.O. F ees b per HB/L c (1 B/L assumed) $60

S/Line d Charges $150

India T ax $20

Total O utbound $5,100

Taking t hat total outbound shipping cost of $5,100 per forty thousand pounds, the cost is

approximately $0.13 cents per pound.

Next, t he raw ribbon will be processed into finished cores at a facility in India which

specializes is forming amorphous cores. For this estimate of the costs involved, DOE relied on an

estimate provided by a transformer engineer who has experience costing the conversion from ribbon

to finished core. This conversion cost, including packing the finished cores back into containers for

the return journey, is estimated to be between $0.50 and $1.00 per pound.

Next, t he finished cores need to be shipped back to the U.S. Due to the volume that the

prefabricated cores occupy, the same 40,000 pounds of material must be returned in two containers,

as approximately half the space inside the forty­foot containers cannot be packed, since it is

occupied by the core windows. Those two containers are shipped from India to the US pacific coast,

a AES ­ Shipper's Export Declaration (SED) information now must be filed electronically with the U.S. Department of

Census' Automated Export System (AES). The system is free to use and the SED information may be filed by the

shipper at their option, avoiding the charge.

b Delivery Order fee covers working with the truck line to arrange delivery of the container, setting appointments, etc.

House B ill Of Lading ­ issued by the freight forwarder/consolidator. This document: (1) provides proof of the

contract for carriage; (2) acts as a receipt for the goods shipped; (3) acts as the freight invoice; and (4) acts as an

insurance certificate, if insurance is requested. In the case of ocean freight they are generally documents of title.

d Ship Line Charges ­ Fee charged by the steam ship line once the container is released covering cleaning, manifestation,

etc.

5­57 cand then to a location 1,500 miles from the shore. That distance was selected because it is

approximately halfway across the country. The following table quantifies this estimate of the cost.

Table 5 .7.2 Forty­foot Container from Guragaon, India to Inland US Location

Item Cost ( US$)

Freight C harges Door to Door (1500 miles in from Pacific coast) $5,200

Courier $55

Customs C learance $150

ACD a per B/L (1 B/L assumed) $25

U.S. I mport Duty (listed as free at this time) $0

Total I nbound (per container) $5,430

Total I nbound (both containers) $10,860

Taking t hat total outbound shipping cost of $10,860 per forty thousand pounds, the cost is

approximately $0.27 cents per pound.

Finally, t here would insurance associated with the shipment, which would be approximately

$520 for the outbound journey (assuming an $80,000 value) and $780 for the inward bound journey

(assuming a $120,000 value). Thus, the insurance costs are approximately $0.03 per pound.

Table 5 .7.3 Summary of Shipping and Processing Costs for Finished Amorphous Core

Raw Shipping t o Process t o Shipping t o Insurance Total

Ribbon* India Core US

$0.80 t o $0.13 / lb $0.50 t o $0.27 / lb $0.03 / lb $1.73 t o

$0.90 / lb $1.00 / lb $2.33 / lb

* This r aw ribbon price was provided by Metglas as their five year average price per pound (2006).

DOE reviewed its pricing gathered by OPS (see section 5.4 in this chapter) and found that

the finished core prices that OPS estimated for the five year average 2002 to 2006 of $2.14 / lb were

well within the range of what would be considered reasonable when compared to the shipping

estimate from Matrix Power, Inc.

a ACD is added by the agent in Delhi and stands for Advanced Cargo Declaration. This is an electronic notice by the

forwarder or ship line to the US Customs Service. The requirement for this notice flows from 9/11. On 31 October

2002, the US Customs Service issued a final rule requiring a vessel to provide an electronic cargo declaration 24 hours

before the cargo is loaded on board.

5­58